The 8.6 BLK Flash Hider by Q is a Quickie Fast-Attach flash hider compatible with the PORQ CHOP and short CHOP silencers by Q. 5/8x24 features 13/16 in flats, and 1/2x28 features 3/4 flats for easy install and removal. These flash hiders do not have a tapered thread. Product Specifications Weight: 2.1 Oz. Overall Length: 2.13 Inches Material: 17-4 Stainless Steel Threads: 1/2-28 (8.6) Installation Instructions Remove any muzzle device, shims, and/or crush washers from your host firearm. Clean and degrease the barrel muzzle threads. Apply Rocksett thread locker to the muzzle device. Using a thin wrench at the appropriate size, torque the Flash Hider to 40 ft-lbs. 13/16 in wrench required for installation.