1. The IN- input terminal is connected to the output port of the charger2. RTZ-clear button, press the button for 3-5 seconds to clear the screen display3. The OUT-output end is connected to the USB port of the data cable4. Input voltage display window (3-9V) accuracy 1%5. The accuracy of the charging current display window (0-3A) is 1%6. Battery capacity display window (0-99999MAh)7. Working time display window (0-99H) unit minute8. The working time and air volume display have memory function after power failureModel: KWS-V20Product size: length 59mm (with USB 73mm) x width 23mm x height 13.5mmVoltage: Input/Output Voltage: 3-9V; Voltage Resolution: 0.01VCurrent: Input/Output Current: 0-3A; Current Resolution: 0.01AAccuracy: 1%Line loss: about 0.1color:BlueMaterial:ABSPackage Contents:1 x USB voltage and current testerOnly the above package content, other products are not included.Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.