& 12304;Manual State Function& 12305;: Long Press the button for 3 seconds, the BLUE led will be On, and the manual mode is on. Press the button each time, you can complete the circuit connection and disconnection. Circuit switched on the red indicator, voltmeter lights up at the same time. Switched off the red indicator, voltmeter lights off. & 12304;Auto State Function& 12305;: Long press the button for 3 button again, the BLUE led will be Off, the Auto mode is on. Voltage exceed 13.3V: Circuit will be automatically connected. Voltmeter Indicator ON. Voltmeter lower than 12.7V: Circuit will be automatically disconnected. Voltmeter Indicator Off. & 12304;Voltage Display& 12305;: This dual battery isolator is constructed with a voltmeter which will display the real-time voltage. If you connect 2 batteries, then the voltmeter will display the battery that has high voltage. The smart battery isolator is universal fit for truck, UTV/ATV, boat, marine, bus, etc. & 12304;Voltage Sensitive Relay& 12305;: Cut-in voltage: 13.3V and Cut-out voltage: 12.8V. Ensure the main battery is always charged so that you won’t worry about the the battery will drain out and stuck on the road. Very convenient and safe to use.