This is a Advanced Technology known as the Mil-Spec, model A.5.10.2240.
The Advanced Technology Int. Military-Spec Buffer Tube Assembly fits most AR-15 and AR Variants. It is not compatible with .308 Rifles. It is constructed of Military Type III Anodized" 6061 T6 Aluminum and is virtually indestructible. This package includes a Steel Military Grade E-Coated Castle Nut and Locking Ring along with a AR-15 Recoil Plug & Buffer Spring. Made in USA.
Features:
Fits most AR15 and AR Variants
AR-15 Military-Spec Buffer Tube
Virtually indestructible