The AR-STONER SOPMOD Stock Assembly is perfect for upgrading an existing AR-15 or building a new carbine rifle. The buffer tube is machined from 6061-T6 aluminum and given a hard coat anodized finish to withstand years of abuse. The 6-position telescoping stock features a built-in flush cup to mount your favorite rifle sling.The AR-STONER Stock Assembly comes ready to be mounted onto your AR-15 (Mil-Spec Diameter) carbine right from the package! Includes:Adjustable Stock6-Position Carbine Buffer TubeBuffer Tube SpringRecoil BufferCastle NutEnd Plate Features6-Position Collapsible StockAnodized Finish Buffer TubeMil-Spec Diameter