FAB ARMS AR-15 Mil-spec buffer / receiver extension tube has the correct 1.148" outside diameter to ensure proper fit of adjustable mil-spec carbine stock. Allows you to install a mil-spec stock on a commercial carbine, convert a rifle with a fixed A2 style stock to an adjustable M4 stock, or complete a custom build.
The extension tube offers outstanding ease and flexibility in setting the buttstock length. Precision machined from strong, lightweight aluminum, then hardcoat anodized with a hard, wear-resistant matte black finish.