TAPCO INTRAFUSE AR MIL-SPEC Receiver Extension Build Kit (Pre-Owned) Make an offer! Sold As Is Signs of wear as seen in pictures. Tapco, Inc. Mil-Spec Black Buffer Tube, Spring, Carb Buffer, Castle Nut, Tapco AR End Plate Sling Adapter ZAR09106 All receiver extensions are not equal, and the INTRAFUSE tube is second to none. The best Mil-Spec extension available today, our tube is impact extruded, producing a much stronger part. This is done using 7075 T6 Aluminum, the same material as most AR receivers. INTRAFUSE didn’t skip any steps on the finishing process either. The inside of the tube is coated with Mil-Spec dry film lubricant that not only keeps the action quieter; it reduces metal-on-metal contact, extending the service life of your buffer. While most other tubes are anodized or have no finish, the outside of the INTRAFUSE tube is grit blasted to leave a non-reflective surface, then coated in Mil-Std 171 Lusterless Black for a smooth matte finish. Unlike many of our competitors, our tubes are 100% made and finished in the U.S. We’ll even supply a certificate of origination; you won’t find that anywhere else! Manufactured from 7075 T6 Aluminum Coated in Mil-Std 171 Lusterless Black Inside coated in Mil-Spec Dry Film Lubricant 100% U.S. Made Includes: -Mil-Spec Black Buffer Tube -Spring -Carb Buffer -Castle Nut -Tapco AR End Plate Sling Adapter