Gemtech Tri-Lock .338 Lapua Muzzle Brake for Arrow QM Suppressor M18x1.5RH Black. 338 ARROW Muzzle Brake is for users who want less felt recoil less muzzle climb and faster follow up shots. The .338 Tri-Lug Quick Mount is for the GEMTECH ARROW Silencer and comes in multiple thread pitches. Specifications for Gemtech Tri-Lock .338 Lapua Muzzle Brake for Arrow QM Suppressor: Manufacturer: Gemtech Color: Black Caliber: .338 Lapua Magnum Additional Features: Quick mount for Gemtech Arrow Package Contents: Gemtech Tri-Lock .338 Lapua Muzzle Brake for Arrow QM Suppressor Gemtech 12144: Tri-Lock .338 Lapua Muzzle Brake for Arrow QM Suppressor M18x1.5RH Black