Permits current to be carried by either of 2 batteries, by 2 batteries simultaneously or cuts off all current at source. Ignition protected. Plastic case, knob and insulator. Four positions: OFF, ON-#1 Battery, ON-both batteries, and ON-#2 battery. Rating 6-36V DC; 310A Continuous, 500A intermittent 3/8″ copper studs Size 6″ flange diameter , Overall Height 2-5/8″ Installation surface mount or install through a panel with a 3-5/16″ dia. hole UL Listed. Marine UL Listed