Advanced Technology A5101050: The Advanced Technology AR-15 civilian buffer tube assembly package fits most AR-15 and AR variants. It features a 6-position, 7.8\" hard-coat anodized 6061-T6 aluminum buffer tube with a slanted back and commercial thread and tube diameters of 1.17\". This assembly also comes with an AR-15 recoil plug, buffer spring, and a steel castle nut and locking ring.