The M4SD Flash Comp optimally combines the functions of three traditionally separate classes of devices- Muzzle Brakes"" Tactical Compensators"" and Flash Suppressors. The M4SD II Flash Comp achieved a perfect 5 out of 5 in National Tactical Officers Association testing to achieve the rare"" coveted"" NTOA Gold seal of approval granted to devices which achieve perfect evaluations. Compatible with the M4SD series GATE-LOK suppressor interface the Flash Comp provides a sacrificial baffle to increase the service life of your silencer. It is also pre drilled"" and 2.25"" length for 14.5"" to 16"" permanently attached"" Non-SBR"" M4 carbine builds. For optimal flash reduction we recommend 14.5"" or longer barreled host weapons. Extreme durability"" low concussion flash and recoil reduction are the wave of the future- the Flash Comp provides an elegant solution to a complex problem. Includes shim set and over-travel stop washer (for mounting to suppressor).