SMAKN&reg; 2-wire Small 0.4" BLUE LED Digital Voltmeter Dc 1.7-25v Lithium Ni-mh Battery Power Monitor Measuring range: DC 1.7-25V Power supply: No power supply(common with measure voltage) Display: three 0.4" LED digital tube Display color: BLUE Allow error: 1% (+ / - 1 digit)