The best ops 12/AE pattern mount ever made- you could try and debate it but you'd be wasting your time. - The OTB Muzzle Brake works the same as our standard OTB mount only with a built in muzzle device. Made from H900 heat treated 17-4 steel this one piece adapter will allow you to mount your OPS 12th model OCM5 or AEM5 to ANY barrel with 1/2×28 threads that is .75 or less OD and a minimum of 2.05 of exposed barrel MEASURED FROM THE SHOULDER. - Pick your flavor of black nitride coated or raw heat treat slap it on your rifle and go- no custom collars or custom barrel work needed. - DO NOT USE A CRUSH WASHER WITH THIS MUZZLE DEVICE OR IT VOIDS ALL WARRANTY. - It comes with a shim kit for timing in the box and this shim kit is the only approved method for timing. The reason the OTB-MB costs more than the OTB-FH is because it comes with the shim kit whereas the OTB-FH does not need timing.