USED Forward Controls Design Flash Hider .223 Remington 1/2x28 Nitride Black LH. 223 1/2 x 28 (internal) flash suppressor / suppressor mount for 1x16 LH (external) threaded sound suppressors and suppressor adapters. Based on the venerable and classic 6315 which uses the A2 form factor (flash suppressor / compensator with 5 ports from 3 to 9 clock and a closed bottom) 6315RF LH is compatible with 1x16 LH sound suppressors and suppressor adapters. It features internal grooves for improved flash suppression these grooves are functional and not decorations. The grooves serve to reduce both the immediate flash and the secondary flash. However the small difference we'd rather have the reduction than without. As with other muzzle devices Forward Controls Design produces it has the MIL standard 3/4 flats any in spec any known good AR15 armorer's wrench can be used to install or remove. A blind hole is drilled behind the external 1x16LH threads for users that want to pin and weld the 6315RF-A1 LH in place. Threaded for 1/2x28 barrels 6315RF LH has 1x16 LH threads for suppressors with 1x16 LH threads such as CAT's WB 1x16LH QD (model CAT/WB/A1) or adapters with 1x16 LH threads such as CAT/TSF-X. Do not use a crush washer if this is going to be a suppressor host. Specifications for Forward Controls Design 6315RF-LH Flash Hider: Manufacturer: Forward Controls Design Color: Black Caliber: .223 Remington Finish: Nitride Fabric/Material: 17-4 Stainless Steel Threads per Inch: 1/2x28 Length: 1.755 in Weight: 2.45 oz Package Contents: Forward Controls Design 6315RF-LH Flash Hider Single use packet of Rocksett Forward Controls Design 6315RF LH: 6315RF-LH Flash Hider .223 Remington 1/2x28 Nitride Black