Cole Hersee 74600-02-BP Dimmer & Rheostat Switch For 12V DC negative ground system, 14.7V DC maximum. 4A Variable intensity between dim and bright Low heat buildup due to solid state construction. Intensity settings are not load-sensitive. Mounting stem: 7/16" -28 thread, .45 (11.43mm) long Housing: diecast, 1-9/16" dia..883" long O-ring seal in shaft. Knob: Black plastic with metal insert and set screw, imprinted with variable symbol in white.