Features: 1. The IN input terminal connects to the charger's output port. 2. RTZ clearing button: Press for 3-5 seconds to clear the screen display. 3. The OUT output connects to the data cable's USB port. 4. Input voltage display window (3-9V) with 1% accuracy. 5. Charging current display window (0-3A) with 1% accuracy. 6. Battery capacity display window (0-99999mAh). 7. Working time display window (0-99H) in minutes. 8. Working time and volume display retain memory after a power failure. Model: KWS-V20 Product Size: Length 59mm (73mm with USB) x Width 23mm x Height 13.5mm Voltage: Input/Output Voltage: 3-9V; Voltage Resolution: 0.01A Current: Input/Output Current: 0-3A; Current Resolution: 0.01A Accuracy: 1% Line Loss: Approx. 0.1 Color: Blue Material: ABS Package Contents: 1 x USB Voltage and Current Tester Note: Light reflection and different displays may cause the color of the item in the picture to differ slightly from the real thing. The allowable measurement error is +/- 1-3cm.