These delrin donuts are designed to take up the fore-aft slack of the stock lower a-arm bushings. The stock lower arms have a rubber wear pad that, wears out, over time and can sometimes "clunk". These spacers slip in to renew the life of the wear pad and reduce the forward/backward movement. They come 4 to a set, 2 per lower arm. You will need to remove the lower a-arm bolts/cam bolts to install. These will not change the alignment as long as the cam bolts are put back where they were when removed.