Ohmite massive power tap switch type 312-3 is a 3 position panel mount rotary switch that is rated 30Amps @ 300VAC. Has "D" shaft for knob and mounts via the 3 flat-head countersunk machine screws into metal panel. Overall diameter 3.31" - Depth behind panel is 2.25". Ceramic case with massive solder eyelets. Non-shorting type with slow breaking and "Quick Make" action. New - Retails for $170.