Digital Voltage Meter 12V, DROK LED Display Voltmeter Panel Precision Variable 2 Wires 3 Digits DC3.5-30V Voltage Tester 12V/24V Volt Reader Gauge Car Vehicle Solar Boat Battery Monitor Detector DROK digital voltage meter is designed with small size (48 x 29 x 21.5 mm) and wide voltage measuring range is DC3.5-30V. The voltmeter panel is two-wire connection, simple and convenient, with high accuracy of +/- (0.5% + 2 Digit). Our battery meter requires no extra power supply, meaning the tested voltage could work as a power supply. This volt reader module is not fit for 24V truck for the voltage of a fully-charged truck battery is above 28V. The voltage tester is with anti-reversed connection protection prevents the meter from burning, hence safe to use.