Tiger Rock AR-10 .308 Pineapple Muzzle Brake 5/8inx24. 308 / .308 Pineapple Muzzle Brake delivers The .308 / .308 Pineapple Muzzle Brake features two 5/8" machined stainless steel o-ring mounts to fit standard flash hider threads. Simply install and adjust the included crush washers to achieve the perfect cam-over-cam angle and ensure solid lock-up at the rear o-ring position. The port size can be fine tuned with the included shims to achieve a perfectly smooth engagement surface with no sharp edges or angles to cause damage to the tail stock. Package Contents: Tiger Rock AR-10 .308 Pineapple Muzzle Brake 5/8inx24 Tiger Rock MBR48: AR-10 .308 Pineapple Muzzle Brake 5/8"x24 (NEW)