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 Mfg: Advanced Technology