5 - 15V Voltage Measuring Range - When it is lower than 5V, the number is displayed, but the surrounding lights are not bright. Shows very accurate voltage and with the bright display. LED will alarm flash if the voltage is higher than 15V. Simple Twist & Lock Design - This Genuine Marine mini voltage gauge fits in a 1.2in diameter panel hole, a nylon retaining nut holds the meter in place. Twist-and-Lock system. Mini size and easy to install, great for checking Voltage. Best Accessory - Can directly replace the original function of the control panel, upgrade the panel. Used to monitor the storage-battery voltage, with reverse connection protection, it won’t burn out even if wires are reversely connected.Timely grasp the state of your battery between full charged and discharged.
eBay