Tapco TAP22058 Buffer Tube Kit. Includes a 6-position buffer tube, carbine buffer, buffer spring, castle nut, and TAPCO Endplate/Sling adapter for a complete buffer-tube assembly. Built to Mil-Spec standards for reliable performance. The 6-position buffer tube allows adjustable length of pull; carbine buffer and buffer spring provide smooth cycling; castle nut secures installation; Endplate/Sling adapter adds sling attachment options. Not available for shipping to Illinois or Washington.