This kit is everything you need for the rear of your AR pattern rifle to attach your 6 position stock. These Mil-spec kits include a 6 position buffer tube, castle nut, end plate, buffer and spring. Pair it with a Luth MBA-3 to complete your UPR. The LUTH-AR Carbine Buffer Assembly is a wear-and-tear resistant and corrosion resilient kit for your AR-15.  They are constructed from aircraft grade aluminum with rolled threading that will outlast and outperform the competition. The LUTH-AR kit comes complete with buffer spring, 3.2oz carbine buffer, castle nut, and end plate. These kits are MADE IN THE USA.