The Taper-Lok muzzle devices are designed to work with Sig Sauer Silencer SRD-QD models. The dual taper (both at the shoulder of the barrel and at the suppressor) creates the most repeatable system for mounting a suppressor on a rifle to date! Gone are the days of shimming a muzzle brake as well. This new system from Sig is a two piece mount that allows the end user to torque the suppressor mount onto their barrel and replace and time the "muzzle device" to their preference (flash hider, 2 or 1 port brake).