Sorbothane¨, a one-of-a kind visco elastic polymer, has been medically and scientifically proven to be the finest cushioning material available today . Kick-Eez pads reduce more recoil and do it better than any other pad. Less recoil reduces flinching, eases sore shoulders or cheeks. By reducing the rebound effect of the first shot, second shots are quicker and more accurate. Pad will not "bottom out" as other materials tend to do even after thousands of compressions. This pad was designed to accommodate stocks that have been shortened. The screw holes are spaced only 2 3/4" apart which allows for trouble-free mounting. One size and one thickness only.