The Firestone 2176 Ride-Rite Air Bag Helper Springs provide load support on your 2011-2012 GM C3500HD & 1999-2020 Ford F-350/450 through the use of air pressure that can be adjusted for changing loads. Mounting between the frame and suspension of your truck, these Air Bag Helper Springs will enhance ride characteristics by reducing inter-leaf friction. The easy-to-adjust bags feature individual inflation valves that allow for separate side-to-side or front to rear adjustment, these will keep your truck level when carrying off-center loads. These heavy-duty convoluted air springs will handle all leveling needs with load carrying capacities between 3,200-5,000 lbs per set. Each air spring is pressure tested before leaving the factory. FEATURES: Adjustable From 5-100 PSI Level Front-To-Rear & Side-To-Side Provides Additional Loaded Stability Maximize Vehicles Load Carrying Capacity INCLUDES: Air Springs Upper & Lower Brackets Inflation Valves & Air Line . Instructions, Hardware & Fittings Applications: 2011-2012 GM C3500HD Cab & Chassis 2WD/4WD (Wide Track Only) 1999-2008 Ford F-350 Cab & Chassis 2WD/4WD 2017-2020 Ford F-350 Cab & Chassis 2WD/4WD 1999-2020 Ford F-450 Cab & Chassis 2WD/4WD Not for use on any models with in-bed hitch.