For variable intensity control of panel and interior vehicle lighting. For 12V DC negative ground systems, 14.7V maximum. Black plastic knob with metal insert and set screw . Knob imprinted in white with the SAE variable symbol. Diecast case, 1 9/16" (39.7mm) diameter, 0.88" (22.4mm) long. Two wire leads (load and battery) 1 25/32” (45.2mm) long. Duty cycle: 1 - 99%.