Best Firman Open Frame Inverter Generators Reviewed for 2026

The Evernexta H4500iDR is a 4800W portable inverter generator purpose-built for homeowners seeking reliable emergency backup power and outdoor enthusiasts needing portable energy for camping or RV trips. With its combination of substantial power output, quiet operation, and clean inverter technology, this unit fills a practical niche for those who want backup power without sacrificing peace and quiet.

The standout feature is undoubtedly the noise level. At 59 dB from 23 feet away, users report that normal conversation remains possible, a remarkable achievement for a 4800W generator. The ECO mode further reduces noise and fuel consumption during light loads, making it genuinely usable in residential neighborhoods and campgrounds. The inverter output maintains less than 3% THD, ensuring sensitive electronics like refrigerators, routers, and phone chargers remain protected from power fluctuations.

Build quality reflects a practical, user-focused design. The 55-pound compact frame with integrated handle makes transport manageable for most adults, while the multiple outlet configuration (2x 120V AC, 1x 12V DC, 1x 30A RV) eliminates fumbling with adapters in most scenarios. The 2-gallon fuel tank delivers up to 9 hours runtime at 25% load, sufficient for overnight outages or full-day camping excursions. Controls are intuitive and setup requires minimal effort.

Potential drawbacks include the open frame design, which offers limited weather protection for outdoor storage, and the 2-gallon tank capacity that necessitates refueling for extended multi-day operations. As a relatively newer product line, it has fewer long-term user reviews compared to established competitors, though current feedback is uniformly positive.

The Evernexta H4500iDR delivers genuine value for homeowners and outdoor enthusiasts prioritizing quiet, clean backup power. It's an excellent choice for those who've rejected traditional generators due to noise concerns or those with sensitive electronic equipment to protect.

Power Output: 4800W peak (starting), 3500W running continuous

Inverter Technology: Clean power output, less than 3% THD

Fuel Type: Gasoline with 2-gallon tank capacity

Runtime: Up to 9 hours at 25% load

Noise Level: 59 dB at 23 feet (ECO mode reduces further)

Outlets: 2x 120V AC outlets, 1x 12V DC port, 1x 30A RV outlet

Engine: 223cc displacement

Dimensions: 15.56 inches L x 19.31 inches W x 18.32 inches H

Weight: 55 pounds

Warranty: 2-year manufacturer coverage, optional 3-year Evernexta Care Service Plan available

Emergency Home Backup: Provides sufficient power for essential devices during residential power outages, keeping refrigerators, lights, routers, and phone chargers operational through the night.

Camping Trips: The quiet 59 dB operation makes it campground-friendly, powering lights, chargers, and small appliances without disturbing nearby campers.

RV Travel: The 30A RV outlet with proper adapter enables integration into RV electrical systems for extended off-grid capability.

Outdoor Events: Powers outdoor entertainment setups, tool charging stations, or temporary worksite power needs with minimal noise impact on surroundings.

Sensitive Electronics Protection: The clean inverter output makes it ideal for protecting valuable equipment like computers, medical devices, and precision electronics that require stable power.

The FIRMAN WH02942 is a 3200W dual fuel portable generator engineered for RV enthusiasts, campers, and homeowners seeking dependable backup power without excessive noise. With its innovative dual fuel capability, users can switch between gasoline and propane based on availability and preference, making it an exceptionally practical choice for extended trips or emergency preparedness.

The standout feature is undoubtedly its whisper-quiet 58dB operation at 25% load, which rivals many premium generators and opens access to noise-restricted campgrounds and national parks where standard generators are prohibited. The 171cc 4-stroke engine delivers 3200W starting power and 2900W continuous output, sufficient for running multiple appliances, power tools, and RV systems simultaneously. With a 1.8-gallon fuel tank providing up to 9 hours of runtime at partial load, extended use between refueling sessions is easily achievable.

Build quality reflects Firman's reputation for engineering excellence. The cast iron sleeve engine sleeve ensures durability, while electric start with recoil backup provides reliability in all conditions. The control panel is thoughtfully designed with a dedicated TT-30R 30A RV outlet, duplex household outlets, USB port, and 12V DC output. Low oil shutdown protection automatically prevents engine damage from inadequate lubrication.

The primary consideration is the 1.8-gallon tank capacity, which necessitates more frequent refueling during continuous operation compared to larger generators. Additionally, at 90 pounds with dimensions of 23.2x17.8x17.9 inches, this unit requires adequate storage space and may be challenging to maneuver in compact vehicles, though included wheels and folding handle improve portability.

The FIRMAN WH02942 represents an excellent investment for anyone prioritizing quiet operation, fuel flexibility, and RV compatibility. Its comprehensive feature set, reliable engineering, and 3-year warranty make it a compelling choice for camping, home backup, and outdoor power needs where noise considerations matter.

Power Output: 3200W starting watts, 2900W running watts at 120V, 60Hz
Engine: 171cc 4-stroke with cast iron sleeve, electric and recoil start
Fuel Options: Gasoline or propane with dual fuel system
Tank Capacity: 1.8 imperial gallons with up to 9 hours runtime at 25% load
Outlets: TT-30R 30A RV outlet, dual household outlets, USB port, 12V DC port (5 total)
Noise Level: 58dB at 25% load
Dimensions: 23.2L x 17.8W x 17.9H inches
Weight: 90 pounds with wheels and folding handle
Warranty: 3 years
Included: 12V cord and float charger, LP regulator with 5.5-foot hose, 12-ounce oil bottle with funnel, spark plug wrench

Who Should Buy This Generator? The FIRMAN WH02942 is ideal for RV and camper owners, frequent outdoor enthusiasts, and homeowners seeking backup power with minimal noise impact. It excels in noise-restricted environments like campgrounds and residential areas.

Dual Fuel Advantage: The gasoline and propane capability provides significant flexibility. Propane burns cleaner, stores longer without degradation, and is often easier to obtain during emergencies. Gasoline offers better power density for the same volume.

Runtime Considerations: The 9-hour runtime at 25% load assumes partial operation. Full-load runtime will be considerably shorter, typically 4-5 hours. Calculate your actual power needs and refueling intervals before purchase.

Noise Comparison: At 58dB, this generator operates at conversational volume levels, making it significantly quieter than standard portable generators (typically 75-90dB). This single feature often justifies the investment for campground use.

Maintenance: Regular oil changes, fuel stabilization for off-season storage, and annual spark plug inspection ensure long-term reliability. The included oil bottle and maintenance accessories support easy upkeep.

The GENMAX GM10500XiT is a premium tri-fuel inverter generator designed for homeowners, contractors, and RV enthusiasts who demand reliable backup power without compromise. With 7800W continuous output and 10500W peak capacity, it handles everything from essential home appliances to construction site equipment while maintaining the portability expected from modern generators.

What sets this model apart is its exceptional fuel efficiency and flexibility. The tri-fuel design lets you switch between gasoline, propane, and natural gas based on availability and cost, while the advanced combustion chamber optimization delivers less than 370 grams of fuel consumption per kilowatt-hour. Real-world testing confirms a 13.5-hour runtime at 25% load, meaning extended backup power without constant refueling interruptions.

The control panel combines user-friendly design with intelligent features including a digital display for real-time monitoring, USB ports for device charging, battery charging capability, and remote start functionality. The clean power output with THD below 3% ensures your sensitive electronics like laptops and smartphones operate safely. Safety features including CO alarm monitoring and automatic shutoff provide peace of mind during operation.

Build quality is robust with high-quality materials and an advanced cooling system designed for demanding conditions. The included accessories (rain cover, hoses, wrenches, remote control) and comprehensive 3-year warranty with lifetime technical support demonstrate GENMAX's commitment to customer satisfaction. While the 120.9-pound weight requires careful handling, the construction and feature set justify the investment.

The GENMAX GM10500XiT represents excellent value for serious backup power needs. Whether powering your home during outages, running construction equipment, or supporting RV adventures, this tri-fuel inverter generator delivers reliable, efficient, and clean power when it matters most.

Power Output: 7800W rated, 10500W peak
Fuel Types: Gasoline, Propane (LPG), Natural Gas
Runtime: Up to 13.5 hours at 25% load
Fuel Consumption: Less than 370g per kilowatt-hour
Power Quality: THD less than 3% for sensitive devices
Weight: 120.9 pounds
Dimensions: 27.12 inches L x 25.27 inches W x 23.62 inches H
Starting Options: One-button electric, remote start, recoil start
Warranty: 3-year coverage with lifetime technical support

Is this generator right for you? The GENMAX GM10500XiT suits homeowners wanting reliable backup power, contractors powering job sites, and RV owners seeking portable electricity. Its tri-fuel capability makes it ideal for areas with variable fuel availability.

Power Requirements: With 7800W continuous output, this generator handles most household appliances simultaneously. Central air conditioning typically requires 3500-5000W, while whole-house backup needs may exceed this capacity. Calculate your specific needs before purchasing.

Fuel Considerations: The tri-fuel option provides flexibility but requires proper hose and connector setup for each fuel type. Included components cover natural gas and propane connections, simplifying initial configuration.

Maintenance: Regular maintenance ensures longevity. The included magnetic dipstick aids oil level checking, and GENMAX's lifetime technical support helps troubleshoot any issues that arise.

The GenTent Original is a specialized weather cover designed for homeowners, contractors, and property managers who need to run portable open frame generators outdoors during inclement weather. Unlike standard tarps or basic covers, this product is engineered specifically for operational use, meaning your generator keeps running while protected from rain, snow, and harsh elements.

What sets this cover apart is its commitment to safety and performance. It holds NFPA 701 flame-retardant certification and UL V-0 ratings, making it genuinely safe to use while the generator operates at full power. The patented design maintains natural airflow and cooling, so you don't sacrifice generator performance for weather protection. The waterproof, ripstop vinyl canopy sheds rain and snow away from electrical components, while the large access door lets you refuel without removing the cover.

Installation is straightforward thanks to the universal clamp system that requires no drilling or permanent modifications. Most users report setup takes just 3 to 4 minutes once you understand the process. The cover fits open frame generators with perimeters ranging from 78 to 104 inches, giving it broad compatibility across popular brands and models. The material is thick, durable, and tested for sub-zero temperatures without cracking or stiffening.

The main consideration is that this cover requires some care during installation to ensure proper fit and height adjustment. Additionally, the plastic clamps warrant occasional inspection in extreme cold, though warranty claims suggest this is rarely an issue in practice. The cover also only works with open frame generators, not enclosed models.

Overall, the GenTent Original delivers professional-grade weather protection for generators that need to keep running in tough conditions. If you regularly operate a portable generator in rain, snow, or variable weather, this cover provides genuine peace of mind and electrical safety that standard covers simply cannot match.

Dimensions: 36 inches L x 24 inches W x 18 inches H, packaged weight of 6 pounds

Compatibility: Universal fit for open frame generators with post perimeters from 78 to 104 inches

Materials: NFPA 701 dual-coated vinyl canopy with UL V-0 flame-retardant rated components and ripstop reinforcement

Installation: Tool-free universal clamp system with no drilling required, designed for high wind stability

Water Resistance: Fully waterproof with water-shedding design, tested in rain, snow, ice, sleet, and wind

Model Number: GTOPFUC, UPC 850079658011

Who Should Buy This: Homeowners with backup generators, contractors operating job site equipment, and anyone who needs to run an open frame generator during rain or snow. This is essential if your generator powers critical systems like sump pumps, medical equipment, or security systems during storms.

Before You Buy: Verify your generator's post perimeter dimensions fall within the 78 to 104 inch range. This cover works only with open frame generators, not enclosed or inverter models with solid housings. Check the included QR codes on the box to watch installation videos before setup.

Installation Tips: Allow 3 to 4 minutes for deployment once familiar with the process. Use a scrap piece of 2x4 wood to maintain consistent clamp height for faster setup on repeat uses. Watch the instructional videos first to understand proper positioning and clamp tightening.

Maintenance: The cover requires minimal maintenance. Inspect plastic clamps seasonally, especially before winter use. Store the cover dry when not in use, and consider the Plus or Extreme editions if your area experiences extended UV exposure or extreme cold beyond sub-zero temperatures.

The WEN GN400i is a 4000-watt inverter generator engineered for users who need reliable, clean power for sensitive electronics. It's perfect for RV owners seeking portable backup power, homeowners preparing for outages, and anyone with laptops, phones, or entertainment systems that require stable voltage. The inverter technology eliminates the voltage spikes and drops that can permanently damage expensive devices.

This generator excels with its pure sine wave output, limiting total harmonic distortion to under 1.2% at full load. Real-world testing confirms it handles demanding tasks like running 1500-watt heaters and 24-amp air compressors while simultaneously charging power tools and other devices. The eco-mode feature automatically adjusts engine speed based on connected load, stretching the 1.85-gallon fuel tank to over 7 hours of half-load runtime, making it remarkably economical for extended use.

Build quality stands out with solid construction, excellent fit and finish, and a compact footprint that weighs just 66 lbs. The fully-equipped control panel includes two 120V NEMA 5-20R receptacles, an RV-ready TT-30R receptacle, and dual 5V USB ports. The open frame design prioritizes portability, allowing one person to carry it easily, though it does require covered storage to protect from weather exposure.

The main limitation is the 1.85-gallon tank capacity, which while providing good runtime, requires refueling for extended operations. Additionally, at 3500 rated watts, simultaneous operation of multiple high-demand appliances may exceed capacity. The open frame also offers less weather protection than fully enclosed models.

The WEN GN400i delivers exceptional value for RV owners and homeowners seeking clean, efficient portable power. Its inverter technology, fuel economy, and versatile outlets make it a smart investment for protecting valuable electronics while maintaining reliable backup power. The two-year warranty and nationwide support network provide confidence in long-term ownership.

Power Output: 4000 watts surge, 3500 watts rated continuous
Engine: 212cc 4-stroke OHV, CARB-compliant
Fuel Tank: 1.85 gallons with 7+ hours runtime at half load
Outlets: Two 120V NEMA 5-20R receptacles, one 120V RV-ready TT-30R receptacle, two 5V USB ports
Harmonic Distortion: Less than 0.3% at no load, less than 1.2% at full load
Dimensions: 19.8 inches long by 13.8 inches wide by 18.9 inches high
Weight: 66.1 lbs
Amperage: 26.6 amps maximum
Frequency: 50 hertz
Features: Eco-mode, parallel-ready, low-oil shutdown, overload protection, electronic ignition

Who Should Buy: The WEN GN400i is ideal for RV owners needing reliable onboard power, homeowners preparing for emergency outages, campers requiring portable electricity, and anyone with sensitive electronics requiring clean power. Its 3500-watt continuous output suits most residential backup needs and recreational applications.

Key Considerations: Verify your power requirements before purchasing. A 1500-watt heater, 1200-watt microwave, or 15-amp air compressor can run individually, but simultaneous operation of multiple high-demand devices may exceed capacity. The open frame design requires covered storage to prevent weather damage. Consider purchasing a parallel connection kit if you anticipate needing doubled wattage in the future.

Maintenance Tips: Follow the manual's engine break-in procedure carefully. The generator includes three carburetor jets for different altitude ranges, so adjust accordingly if you operate above 3000 feet. Use premium fuel with fuel treatment for optimal performance. Change oil regularly and store with stabilized fuel during extended periods of non-use.

Warranty and Support: The two-year manufacturer warranty covers defects and failures. WEN maintains a nationwide network of authorized service technicians and provides customer support through their help line, ensuring you have access to professional assistance if needed.

The Champion 4250-Watt Dual Fuel Inverter Generator is designed for users who need dependable backup power without the noise and bulk of traditional generators. Whether you're an RV enthusiast, homeowner preparing for emergencies, or someone who tailgates frequently, this unit bridges the gap between portability and performance with its innovative hybrid design.

The standout feature is the dual fuel capability, allowing you to switch between gasoline and propane with a simple dial turn. This flexibility is particularly valuable for emergency backup since propane doesn't deteriorate in storage like gasoline does, ensuring your generator starts reliably when you need it most. The 224cc engine delivers 4250 starting watts and 3500 running watts on gasoline, with runtime extending to 22 hours at quarter load. On propane, you get 3825 starting watts and 3150 running watts with 14 hours of runtime from a 20-pound tank. The RV-ready outlet configuration includes a 120V 30A RV plug, two standard 120V outlets, and a 12V DC outlet with dual USB adapter included.

What truly sets this generator apart is its Quiet Technology, achieving just 64 dBA from 23 feet away. This is comparable to normal speech volume and a dramatic improvement over traditional 3500-watt generators. Combined with Economy Mode that reduces fuel consumption and extends engine life, plus Cold Start Technology for reliable ignition in cold weather, this unit demonstrates thoughtful engineering. The clean power output at less than 3% THD means you can confidently power laptops, smartphones, and other sensitive electronics without concern for damage.

Design-wise, Champion reduced weight by 20 percent and decreased the overall footprint compared to their standard models, making transport and storage more manageable. The 79-pound weight is still substantial but reasonable for a 4250-watt unit. The open frame design allows easy security anchoring, and the Quick Touch Panel provides intuitive control access. One consideration is that simultaneous operation of power-hungry appliances requires load management, as reviewers noted running an AC unit and microwave together exceeds capacity in RV applications.

This is an excellent choice for anyone prioritizing reliability, quiet operation, and fuel flexibility. The 3-year warranty and free lifetime technical support from Champion's nationwide service network provide confidence in your purchase. Real-world users consistently praise its performance for remote work setups, boondocking adventures, and emergency home backup power.

Power Output: 4250 starting watts, 3500 running watts on gasoline; 3825 starting watts, 3150 running watts on propane

Engine: 224cc 4-stroke, compression ignition, 60 Hz frequency

Fuel Capacity: 4.0-gallon gasoline tank; compatible with 20-pound propane tanks

Runtime: Up to 22 hours at 25% load on gasoline; up to 14 hours at 25% load on propane

Noise Level: 64 dBA at 23 feet

Power Quality: Clean power, less than 3% THD

Outlets: 120V 30A RV (TT-30R), two 120V 20A household (5-20R), 12V DC automotive with dual USB adapter

Dimensions: 27.9 inches L x 23.4 inches W x 21.7 inches H

Weight: 79 pounds

Warranty: 3-year limited warranty, free lifetime technical support

Certifications: EPA certified, CARB compliant

Is This Generator Right for You? This model excels for RV owners, remote workers needing reliable backup power, and homeowners in areas prone to outages. The dual fuel option makes it particularly valuable for emergency preparedness since propane won't deteriorate during storage.

Power Requirements: At 3500 running watts, this generator can power essential home appliances like refrigerators, sump pumps, and well pumps, though not simultaneously with high-draw items like full-size AC units. For RVs, it handles Starlink systems, computers, small window units, and most standard appliances with load management.

Maintenance Considerations: The 0.6-quart oil capacity with low oil shut-off sensor provides protection against dry running. Follow the recommended 5-hour half-load break-in period and change oil before extended storage. Propane operation requires initial choking and slow valve opening but becomes routine with use.

Parallel Expansion: If future power needs increase, the optional ParaLINK Parallel Kit allows connection of two 3000-watt or higher inverter generators to double your output capacity.

Storage and Transport: At 79 pounds, consider using a furniture dolly for frequent movement. The open frame design allows easy anchoring with cable or chain for security. Propane storage is cleaner and more stable than maintaining fresh gasoline for emergency backup.

The Westinghouse ecoGen10000 is a mid-range portable inverter generator designed for homeowners seeking reliable backup power during outages and outdoor enthusiasts who need dependable electricity at remote locations. With 10,000 peak watts and 7,600 running watts, it bridges the gap between smaller portable units and heavy industrial generators, making it suitable for powering essential home appliances, RVs, and job sites.

What truly sets this generator apart is its inverter technology combined with practical convenience features. The clean power output at less than 3% THD protects sensitive electronics like computers and medical equipment. The remote electric start with included key fob eliminates the frustration of pull-cord starting, while push-button and recoil options provide backup methods. The 420cc 4-stroke engine delivers impressive 12-hour runtime on its 5.28-gallon tank, and the digital VFT display keeps you informed with real-time voltage, frequency, and maintenance tracking.

The outlet configuration demonstrates thoughtful design with six total outlets including transfer switch ready L14-30R and 14-50R connections for direct home integration. The four GFCI-protected 120V outlets add safety for outdoor use. The included never-flat wheels and lift bracket make repositioning straightforward despite the 147.7-pound weight. The comprehensive package includes battery charger, engine oil, tools, and extensive documentation, meaning you can operate it immediately out of the box.

Minor considerations include the two-person requirement for lifting and the need to understand GFCI outlet reset procedures. The CO sensor is an excellent safety feature but requires proper outdoor placement to function effectively. These are manageable tradeoffs for the capability and reliability offered.

The Westinghouse ecoGen10000 represents solid value for homeowners and outdoor users seeking a capable, feature-rich inverter generator with proven reliability and strong customer support backing.

Power Output: 10,000 peak watts, 7,600 running watts at less than 3% THD

Engine: 420cc Westinghouse 4-stroke OHV with cast iron sleeve, electronic ignition, automatic low oil shutdown

Fuel: Gasoline, 5.28-gallon tank with fuel gauge, up to 12-hour runtime

Outlets: Four 120V GFCI 5-20R, one 120V L14-30R transfer switch ready, one 120/240V 14-50R transfer switch ready

Display: Digital VFT showing voltage output, frequency, and lifetime hours

Starting: Remote electric start with key fob, push-button start, recoil backup

Dimensions: 24 inches L x 26.7 inches W x 25.1 inches H

Weight: 147.7 pounds

Features: CO sensor, never-flat wheels, handle, lift bracket, 3-year limited warranty

Best For: This generator suits homeowners wanting transfer switch ready backup power, RV owners needing extended runtime, and outdoor workers requiring clean power for sensitive tools and equipment.

Consider This If: You need transfer switch capability for whole-home backup, want inverter protection for electronics, prefer remote start convenience, or require 12-hour runtime between refueling.

Skip If: You need ultra-portable lightweight equipment under 100 pounds, require natural gas fuel, or need output exceeding 10,000 peak watts.

Setup Tips: Place outdoors at least 20 feet from windows when using CO sensor. Familiarize yourself with GFCI outlet reset buttons before first use. Run fuel stabilizer through the system before storage. Use the included fuel shutoff valve to run the tank dry before extended storage to prevent carburetor issues.

The FIRMAN W02985 is a 3200W portable inverter generator engineered for camping enthusiasts, RV owners, and homeowners seeking dependable backup power. With its advanced inverter technology and 193cc gas engine, this unit delivers stable, clean power suitable for electronics, appliances, and sensitive devices that require consistent voltage output.

The standout feature is its remarkably quiet operation at just 58 dB at quarter load, making it one of the quieter options in its class. Multiple starting methods, including remote start, electric start, and recoil backup, ensure you can power up in virtually any situation. Real-world users praise its performance for running RV air conditioners and powering camping equipment without issue, while the 10-hour runtime on a 1.8-gallon tank keeps you going through extended trips.

Build quality reflects FIRMAN's reputation for durability, with a sturdy iron and cast iron construction designed to withstand outdoor conditions. The compact dimensions and portable design make it manageable for most users, while the RV-ready power panel with covered outlets adds practical safety features for outdoor connections.

However, potential buyers should note mixed customer experiences regarding long-term reliability and warranty support. Some users report issues after months of ownership, while others have successfully used multiple FIRMAN units in harsh environments. Customer service experiences vary significantly, suggesting you should clarify warranty terms before purchase.

The FIRMAN W02985 represents a solid choice for those prioritizing quiet operation and clean power output for camping and emergency backup. It excels in noise-sensitive environments and delivers the runtime needed for weekend adventures. Consider your specific needs carefully and research current customer feedback, as experiences with this model appear variable.

Power Output: 3200W starting watts, 2900W running watts
Engine: 193cc 4-stroke gas engine with 171cc displacement
Starting Options: Remote start, electric start, recoil start
Fuel Tank: 1.8 gallons with up to 10-hour runtime
Noise Level: 58 dB at quarter load
Power Outlets: 4 total outlets with RV-ready connections
Voltage: 120V, 60 Hz frequency
Dimensions: 23.2 inches L x 17.8 inches W x 17.9 inches H
Included Components: Oil, funnel, tool kit, owner's manual, battery charger, remote control

Best For: The W02985 suits camping trips, RV adventures, tailgating events, and emergency home backup power where quiet operation matters. It works well for powering sensitive electronics like laptops, medical devices, and entertainment equipment.

Consider If: You need a balance between power output and portability. The 2900W running watts handles most camping appliances but may struggle with high-demand devices like large air conditioning units or power tools simultaneously.

Skip If: You require extended runtime beyond 10 hours without refueling, need higher wattage for industrial use, or prioritize maximum customer service responsiveness. Also avoid if you prefer premium warranty guarantees without question.

Key Considerations: Check warranty details with your retailer before purchase. Verify fuel storage procedures and maintenance requirements in your climate. Test the remote start and electric start functions immediately upon delivery to ensure proper operation.