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 Muzzle Brake 5/8x24 TPI up to 308 cal