Unless you are using a tape switch you are better off with the BMT clamp with a 6 slot rail. If you have a tape switch, then either will work but the MOD-C is a little more refined and there is nothing more to buy. It also attaches with only one screw going into a steel threaded insert. If you check out the website you will see how they are built because there is a little graphic cut-a-way on the MOD-C page.