Holdding 2-wire Car 0.56" DC 2.7-30V 12/24V Green LED Small Digital Voltmeter Panel Volt Meter Voltage Gauge with Reverse Polarity Protection Measure voltage: DC 2.7-30V (two wires Access) Refresh rate: about 200mS / times Measurement precision: 0.01V (3-10V); 0.1V (10-30V) Display: Three 0.56" digital LED Tube Operating temperature: -10c to 65c