Now Off Road Air lets you adjust your tires to the terrain without the wait, without the hassle, without the risk. Get your rig ready for the trail the easy way. Our Rapid Air Down system (RAD) valve stem is a complete replacement valve stem. It works with standard guages and air chucks. But it lets you air down faster. Just remove the cap, unscrew the easy-to -turn knurled release wheel two turns, deflate the pressure you want, retighten the release wheel, put the cap back on. Perfect compliment to the SOURCE!