This is what 2A Armament says :
Our AR-15 buffer tubes are in house manufactured and finished with hard anodize for lasting performance.
Billet machined from 6061-T651 aluminum for tighter concentricity than a forging or impact extrusion to reduce potential for bolt carrier binding.
8 position adjustment with machined indicators visible through any stock with a viewing port located at the stock latch pin. Extended positions, increment adjustments have a finer spaced length of pull.
Mil Spec extension diameter of 1.148, and thread diameter of 1.185
Extended carrier support flange that supports the carrier for better anti-tilt performance.
Self aligns with the buffer detent.
Chamfered edges on the stock guide ramps for better feel
Weight 3.45 oz
Note: This item ships as the buffer tube only. A buffer tube assembly with latch plate and castle nut is also available.