Vktech Mini DC 3-30V BLUE 0.36 Inch LED Panel Voltage Meter 3-Digital Self-Powered Voltmeter Power supplydon't need the power supply, direct use of the test voltage as a power supply Measurement range: DC3.0 - 30V The minimum input: 3.0V The maximum input: 30V Operation temperature: -10 ~ +65 Display mode: three 0.36 LED digital tube Display color: Blue Update rate: about 500 ms/time Permissible error: 1% (+ / -1 word) Color: As the picture Physical size: Approx. 23 x 15 x 10 mm (L x W x H, not including installation ear) Lead wire length: Approx. 15 cm