About this item: [Wide Compatibility]--This battery isolators are small and suitable for almost anywhere, for ATV, UTV, Boats, RV's, marine vehicle, truck, caravan [Working Voltage]--Voltage Sensitive Relay (VSR) cuts in at 13.3 volts and cuts out at 12.8 volts to your primary battery is always and ready to run your vehicle [Function]--With the engine running the VSR engage when the starting battery reaches 13.3 Volts and the LED light illuminate. This means that both batteries are now linked and the system is working.Once you turn off your vehicle the system disengage the two batteries as it reaches 12.8 Volts, leaving your main battery safe to again [Important Note]--When connecting accessories to your second battery they are fused within 0.98FT Product parameters: Type: 12V Voltage Sensitive Relay Continuous current: 80-100A Instantaneous current: 125A Current Consumption - Charging: 240mA Current Consumption - Standby: 8mA Detachment delay: 5-10 seconds Recommended Fuse: 80Amp Power stud: M6 copper screw nut Surge Protection: Built-in 1. When the battery power is low, disconnect the auxiliary battery, and first the charging and operation of the main battery. 2. After the main battery is fully , it automatically charge the auxiliary battery without affecting the power supply of electrical equipment. 3. Automatically cut off the connection of the main battery and the auxiliary battery when it is not charging, so there is no need to worry about the engine being unable to due to lack of power. Material: ABS colour: black Package Contents: 3 x battery isolator Only the above package content, other products are not included. Note: Light reflection 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 +/- 1-3cm.