[Wide Compatibility] - Battery isolators are small and fit almost anywhere, for , UTV, Boats, RVs, Marine, Heavy Duty Trucks, Caravans, Off-Road Campers, Yachts [Function] -- With the engine running, the voltage sensitive relay will engage when the starter battery reaches 27.4 volts and the LED indicator will light up. This means the two batteries are now linked and the system is working. Once you turn off your vehicle, the system will disengage both batteries when it reaches 25.6 volts, leaving your primary battery safe to restart. [Important Note] -- When connecting accessories to your second battery, make sure they are fused within 0.98m. Color: Black Material: ABS Package Contents: 1 x Dual Battery Isolator 1 x Screw Accessories Only the above package content, other products are not included. Note: Light shooting and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3 cm.