I installed these on a 2009 F150 4WD Crew Cab to prevent rear suspension sag when towing a 30 foot trailer/toy dump truck. The air suspension works great, fitted the rear of the truck and was pretty easy to install. The system can withstand pressures of up to 100psi, but works well for our needs when installed in the 35-40psi range. The airbags also give me the ability to increase the height of the drawbar that lowers the rear of the toy tractor to make loading the bike easier with the gate down and make it level with the back of the RV floor. The only two complaints I have and why I didn't give it five stars are the air brake quick releases that come with the kit which tend to lose air as they get old. I recommend using a brass compression type 1/4. "X 1/4" 90 degree point fittings on the airbags instead, but couldn't find a compression type for the tire valve stem to inflate or depressurize the air. Another problem is that when there is no load and the system is set to a minimum pressure of 5psi, the rear of the truck will raise.