This receiver extension buffer tube has the Mil Spec outside diameter required by many aftermarket collapsible buttstocks. Teflon black finish is attractive as well as durable.

NOTE: This buffer tube has a slightly angled rear end that resembles a commercial diameter buffer tube, however the outside diameter of the DoubleStar tube does indeed adhere to the Mil Spec diameter. The angled rear surface may interfere with some aftermarket buttstocks by not allowing the stock to engage the first position (fully collapsed) on the tube.

Mil-Spec Vs Commercial:

Buffer tubes come either as Mil-Spec or Commercial diameter. The Mil-Spec buffer tube is 1.148" in outside diameter while the Commercial buffer tube has an outside diameter of 1.168". Different commercial AR-15 manufacturers may choose either type of buffer tube, but the traditional standard is the Mil-Spec diameter.