Gen 2 is a two-piece design that allows the shooter to quickly install or remove their muzzle brake for whatever reason. Say goodbye to crush washers, peel washers or the need for a professional installation. Your hands and a crescent wrench are all that is needed. The LB is a perfect fit for barrels .750 - 1.0 inch in diameter at the muzzle & can handle cartridges up to the 338 lapua. APA Gen II Little Bastard 18x1.5 TPI 30 cal Stainless Steel Muzzle Brake GenII-LITTLE-18x1.5-30-SS