This dual battery relay from Rugged Ridge fits 70-83 Jeep CJ5, 70-75 CJ6, 76-86 CJ7, 81-86 CJ8, and 87-11 Wranglers. The Rugged Ridge Dual Battery Relay Kit is the perfect companion to the Rugged Dual Battery Tray. This relay kit allows you to connect two batteries to your electrical system. Because the last thing you want when your out of the trail or headed to the beach is a dead battery. The three position switch allows you to manage the batteries through the use of the solenoid. Position one is the factory single battery mode. Position two uses the main battery, but charges both batteries. Position three allows both batteries to be used for winches or to crank the vehicle if the main battery is dead.