1. The IN- input terminal is connected to the output port of the charger 2. RTZ-clear button, press the button for 3-5 seconds to clear the screen display 3. The OUT-output end is connected to the USB port of the data cable 4. Input voltage display (3-9V) accuracy 1% 5. The accuracy of the charging current display (0-3A) is 1% 6. Battery capacity display (0-99999MAh) 7. Working time display (0-99H) unit 8. The working time and air volume display have memory function after power failure Model: KWS-V20 Product size: length 59mm (with USB 73mm) x width 23mm x height 13.5mm Voltage: Input/Output Voltage: 3-9V; Voltage Resolution: 0.01V Current: Input/Output Current: 0-3A; Current Resolution: 0.01A Accuracy: 1% loss: about 0.1 color:Blue Material:ABS Package Contents: 1 x USB voltage and current tester Only the above package content, other are not included. Note: Light reflection and different displays may cause the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.