The Muzzle Brake is both multiplayer and singleplayer weapon attachment available in Crysis 3.
Muzzle Brake increase stability, allowing more stable fire while do sustained fire. However, it will increase muzzle flash.
It is useful when attached to SCAR and SCARAB in conjunction with Extended Magazine to allow easier sustained fire. It also useful for Grendel since Grendel has high recoil when using the Burst-Fire mode.