DROK Digital DC LCD Voltmeter Gauge 12V Volt Panel Voltage Monitoring Meter Operating voltage: AC / DC 8 ~ 12V; positive and negative voltage measurement Measuring rang: DC 0- +/- 200mV /2V /20V /200V /500V (Variation Optional) Operating current: &lt;15mA; Measuring rate: 2 times / S Display: LCD, blue backlight, character height 20mm Dimensions: 79 x 43 x 25 mm;Installation hole: 76 x 39 mm