Black anodized, Carrier cradle extentions, Detent-lock prevents tube rotation, 3 drain holes. Mil-Spec 7075-T6 aircraft aluminum Anti-tilt Buffer Tube uses “carrier cradle” extensions to ensure that the carrier is always supported by the buffer tube, even when the bolt is forward. This prevents carrier-tilt and premature wear on the buffer tube. Thusly, the buffer-detent button doubles as a lock that stops the buffer tube from rotating and becoming loose under extreme operation conditions. POF’s desiging also features three (3) extra drain holes for marine environments. Replacement Compatible with All P415 and P416 rifles with 6 position buffer tube. Replacement Compatible with P308 rifles manufactured BEFORE OCTOBER 2012 that used a 6-position buffer tube! New P308 rilfes feature a 7-Position Buffer Tube that utilize the standard AR15 Carbine Buffer and .308 A2 Rifle Length spring. Refer to the first two digits of your weapon’s serial number for the year. If it reads “12-“, please check your rifle’s adjustable stock position count before making your purchase.