2 Wire White Dc 3.2-30v LED Panel Digital Display Voltage Meter Voltmeter By Vstc Measuring Range: DC3.2-30V. Minimum input: DC3.2(Below this voltage,it will show measurement inaccurate, or don't show). Maximum Input: DC30V(please do not exceed 30V, otherwise, the meter would be damaged.). Refresh speed: about 500ms/each time. Size:4.8cm x 3cm x 2.2cm - 1.89inch x 1.18inch x 0.87inch.