DROKxae; 0.36" Voltmeter Gauge 5 Digit DC 0-33.000V 12/24V DC Volt Meter Voltage Tester Monitor with Yellow LED digital Display and 3 Wires for Automotive Vehicle The measurement range is DC 0-33.000V, high precision. Red wire:Power supply+;Yellow wire:Measure voltage+;Black wire:Power Supply-, Measure voltage-. The voltmeter needs independent power supply. Power supply range is DC 3.5-30 V. Measurement accuracy:0.3+ 2words. With reverse connection protection to avoid burning out.