KAK Industry XM177 Flash Hider 556NATO Fits AR-15 1/2x28 Phosphate Finish Clone Correct 1/2x28 Black. Can be used with a crush washer that's hidden in the grenade ring counter bore and not show once installed. Design inspired by the XM-177 Moderator" this extended flash hider will extend a 12.5" barrel to legal non-NFA length when pin and welded. Specifications for KAK Industry XM177 Flash Hider 556NATO Fits AR-15 1/2x28 Phosphate Finish: Manufacturer: KAK Industry Color: Black Caliber: 5.56x45mm NATO Finish: Phosphate Black Threads per Inch: 1/2x28 Features of KAK Industry XM177 Flash Hider 556NATO Fits AR-15 1/2x28 Phosphate Finish Black Clone Correct: 4.678 Overall Length" Package Contents: KAK Industry XM177 Flash Hider 556NATO Fits AR-15 1/2x28 Phosphate Finish