The Tekonsha Model 7001 4-Terminal Battery Switch is a 12V continuous duty insulated cadmium plated isolator with terminal nuts and lock-washers. The 4-terminal insulated isolator is made for use with fiberglass or other non-conductive materials. This unit isolates the starting battery and assures you of primary battery power for starting your engine, provides secondary battery current for auxiliary power, and allows full time charging of both batteries. It also gives you early re-use of the secondary battery. Brand new and in stock.