ZCI Zero Contact Interface Universal T-ConnectorZCI sensor technology and direct connection to the tow vehicle battery, eliminates all electrical connection and interference with the tow vehicle electrical system. Vehicles with 12 volt system only. NO CUTTING OR SPLICING VEHICLE WIRING! Isolates Trailer Light Operation from Tow Vehicle's Electrical System. Works with 2 or 3 wire systems. Works with PWM or Multiplexed systems requiring 2 or 3 wire hookup. Rated for up to 4.2 amps for turn/stop & 7.5 amps for taillight trailer circuits. Works with low side switched vehicles. Integrated auto resetting short & overload protection. Robust design allowsfor interior or exterior mounting. | Tekonsha Circuit Protector