Smart&Cool &reg; LCD Display USB Power Multimeter, Current and Voltage Monitor for Cellphone Battery Capacity Measurement, Power Bank Capacity Measurement, USB Cables and USB Power Adapters Help validate actual tablet/cellphone/power bank battery capacity Convenientyly distinguishes if a USB power adapter is working or not; validate cables; view working voltage and current of USB devices Input Voltage: 3-7V, Input Current: &lt;3.5A, Capacity: 0-19999mAh High precision current calibration Easy to read data on LCD display both day and night