DMiotech DC 100V 10A Digital Voltmeter Ammeter 2 in 1 LED Dual Meter Voltage Ampere Monitor Tester Made of good quality plastic and electronic component material and finished by good technology. Minimum input voltage is below the minimum measurement inaccurate or does not show Maximum input DC 30V (above this voltage burn danger) Display 0.28 Inch LED 3-digital tube; Display color: red; Refresh rate of about 500mS / times Power supply: No power supply; Operating temperature: -10C~65C.