The Flash Hider-QD is designed to mitigate flash when unsuppressed. Flash Hider-QD 556 is compatible with HX-QD 556k" 556" 762" 762 Ti and Magnum Ti suppressors. NOTE: Larger caliber mounts are NOT compatible with smaller caliber suppressors. Smaller caliber mounts ARE compatible with larger caliber suppressors.Features :1/2X28 Thread Pitch"2.7" Long Version, Works on 13.7" Platforms to Bring Barrel to 16" Overall Length (On Barrels with 0.6" Threads),