Mark, I added the bracket when I installed a new Otter switch and saw just how loose the new switch and grommet were in the hole in the radiator. I could pull the switch out with very little force. The bracket is made from aluminum stock bent 90 degrees. I drilled and filed a slot in front to fit over the switch terminal connection. The bracket is held in position just by the pressure of the radiator against the opening in the body. For additional safety, you can bend the other end of the bracket around the radiator side tank. Just make sure that the bracket is tight between the radiator and the opening.
Overall a bit more elegant solution to the standard safety wire wrapped around the switch that I've seen others do.
Joji Tokumoto
Fallbrook, Ca