This is what 2A Armament says :



Our AR-15 buffer tubes are in house manufactured and finished with hard anodize for lasting performance.  

Features include:

    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
    Carbine length
    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.


Buffer Tube - AR15

SKU: 2A-BTU6-1