Receiver extension tube has the correct, 1.146" outside diameter for mounting collapsible buttstocks designed for the smaller, mil-spec tube. Lets you mount a mil-spec stock on a civilian carbine or convert a rifle with A2-style fixed buttstock to collapsible configuration; carbine action spring and buffer assembly required. Allows fast, easy repeatability of buttstock position with five notches on underside to accept the stock’s locking pin and corresponding white position numbers on top visible through the witness hole on many stocks. Precision machined from aluminum bar stock for consistent dimensions that ensure smooth, snag-free sliding of buttstock.

SPECS: Aluminum, hardcoat anodized, matte black. 7-3/16" (cm) long, 1.146” O.D. 7075 T6 Aluminum