Product Features 6-position Mil-spec Diameter Receiver Extension Tube for AR15 Rifles Extension Tube CNC Machined from 6061-T6 Aircraft Grade Aluminum with Precisely Rolled Threads for Durable Thread Engagement with Lower Receiver Underwent the Tightest Tolerance Controls for a Secure Fit and Function with Various Collapsible Stocks Finished in a Matte Black Type III Class II Hard Coat Anodize Includes Mil-spec 6-position Extension Tube, Recoil Buffer, Buffer Spring, Receiver End Plate, and Castle Nut Proudly Designed and Made in USA Product Specifications Material: Aluminum Height: 1.45" Length : 7.25" Weight: 9.3 oz Color: Black