SMAKN&reg; Green 0.28" Mini 2 Wire Dc Voltmeter 2.7~30v Digital Display Voltmeter Gauge LED Voltage Detector Measuring range:DC 2.50~30V Two-wire access Measurement precision:0.01V(3-10V); 0.1V (10-30V) Display:Three 0.28 " LED digital tube Display Color:blue Power supply same Source,self-Power