BANDC Digital Voltmeter Charger Outlet Socket for Car Boat Auto Motorcycle Truck Dc 12v This is a high quality voltmeter for checking the state of your battery and battery charger.The state of your battery between full charged and discharged. Can indicate a poor or bad charging system. Tells whether your battery is holding a charge or not.The meter has easy to read red LED segments and connect to your 12 volt system. It mounts in a 1-1/8 hole in panels up  thick, a nylon retaining nut holds the meter in place. A mounting plate is also included that fits over the front of the meter to hold the meter against panels of any thickness. The socket body is made out of heavy nylon. The meter draws nominally 10 ma. and the range is 0-35 vdc. The meter LED Lamp display is red.