1. The working time and capacity display has a memory function after power off. 2. Press the RTZ reset button for 3 seconds and the screen display will be reset. 3. USB intelligently monitors current and voltage capacity. 4. Portability: This product is small in size, light in weight, and very convenient to carry. 5. : This product is made of high-quality materials, exquisite workmanship, very and long service life. It can also help safe charging and monitoring your charging data in real time. Model: KWS-V21 Voltage: Input/Output Voltage: 4-20V, Voltage Resolution: 0.01V Current: Input/Output Current: 0-3A, Current Resolution: 0.01A Ambient temperature: 60 () Accuracy: 1% Line loss: about 0.1 ohms Colour:transparent black Material:plastic+metal Size:73 x 23 x 13.5mm Package Contents: 1 x USB Tester Only 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.