The X12 Series Muzzle Brakes combine JMac's effective RRD muzzle brake design and a direct thread mount for several popular suppressors as well as their BDS-12 blast shield! This allows you to leave the muzzle device installed and simply thread the suppressor over! Reduces weight, length, and cost compared to QD systems. Direct thread is also the preferred mounting method for accuracy! Product Specs: 1/2-28 Threads X12 - 1.125-28 External Threads 10mm Bore 17-4ph Stainless Steel Black Nitride Requires timing for proper function. Not intended or recommend for barrels shorter than 10.5" When testing these devices, JMac found Mfg: Jmac Customs