Review on Support Car Round Toggle Switch by Mark Caperton

They will not fit a 19mm or 3/4" hole. The diameter of the switch body (which needs to fit through the hole) is 19.9mm. Therefore, for installation you need a hole with a diameter of 20 mm. You will then either have to drill the keyhole to fit the grommets or cut them off. As for the switches, they're decent basic switches. I would have preferred them lower because the specs are so far off, but they're cheap.