If you don't like to read just click on the video to choose the right brake........
The Gen 1 series is meant to be installed by a competent gunsmith. The rear of the brake requires a chamfer to blend perfectly to your barrel. Additionally the gunsmith will back bore the brake for perfect coaxial bore alignment. The end result is absolute mechanical & cosmetic perfection!
The Gen 2 series just makes life simple. Its simple two piece design does not require a professional install if you have a barrel that's already threaded. For the competitive shooter that burns through barrels like toilet paper he can now move the brake from barrel to barrel in about 30 seconds.