I put the PRS on my LWRC 18" DMR and I don't much like it. I have a harder time getting behind the scope than I did with my Vltor Mod Stock. It also effected the balance of the rifle. I will try it again this week end and if I still don't like it I will sell it off. I bought it new for $75 just to give it a try. You need a rifle (A2) buffer extension tube without spacer and an AR rifle buffer and rifle spring. This will add about $45 to the cost of the stock.