They are maintenance free, do not leak air, and do not require airlines or compressors. They are manufactured from proprietary closed micro-cellular urethane providing a smooth and progressive spring rate with superior damping properties.
Springs arrived sooner than expected. About a half hour to install. Ride is a little stiffer than it was. But I used these on a Tacoma before current Tundra and the ride was the same. Haven’t hooked to the RV yet and loaded the truck bed down, but that’s where the difference between OEM bumper and Sumo Springs stand out.
So far very pleased with the Sumo's. I haul firewood rounds, however, with the forests closed here in Calif. the true test will have to wait. They were easy to install, about 30 min. Stiffened the unloaded street ride slightly.