The Sig Sauer Rifle Muzzle Device Collar is a ring that converts tapered barrels to a 90 degree shoulder. This allows for proper timing and torque of muzzle devices designed for traditional barrels.
This collar is used on rifles such as the Sig 716, MCX, and MPX when mounting a flash hider or muzzle break other than those designed by Sig Sauer and Q.
Commonly used muzzle devices that require this collar are those manufactured by SilencerCo, Dead Air, Rugged, Gemtech, SureFire, AAC, and Thunder Beast.