They replace one of the 2 bolts that hold the bottom of each strut to the knuckle. They have an eccentric, and as you rotate them, the entire assembly tilts in and out. You can only put them in and eyeball them as straight up as possible, then drive directly to an alignment shop, who will use them to set your camber within specs.altimafreak said:what the hell are these things and how do I put them in? and how much?? What do they do?? Im lpannin on gettin dz coilovers and kyb struts, so I guess I need them eh??