Fits: Most AR-15 and AR Variants. Not Compatible with AR-10 or .308 Rifles. - AR-15 Pistol Buffer Tube Assembly - Constructed of Military Type III Anodized 6061 T6 Aluminum - Mil-Spec Tube Diameter for Proper Fit to Specified Manufacturer's Range for the Sig Brace etc. - Military Diameter Threads for Maximum Fit into AR-15 Receiver - Vynafoam Padded Tube Cap - Includes Steel Military Grade E-Coated Castle Nut and Locking Ring - Includes AR-15 Recoil Plug & Buffer Spring - Virtually Indestructible - Limited Lifetime Warranty - Made in the USA