Following the release of the G3 BT-REX, we downsized the latest version into the MB-REX. With the same recoild reduction but much improved jump suppresion, this brake is best for rifles with lots of bang.. This brake has been tested on .338 Lapuas by kids as young as 8 years old. Utilizing 3 top ports, 6 angle ports, and 1 perpendicular port will make even the heaviest of loads feel like a pop gun. With the shooters experience in mind, this brake utilizes a reduction in recoil, concussion and sound felt by the shooter. Comes stock in 5/8" x 24 TPI and 3/4" x 24 TPI. I would advise using a 5/8" thread for barrels under .800" OD 3/4" for barrels above .800 OD. Shim kit is included for timing.