Description 1. The working time and capacity display has a memory function after shutdown. 2. Press the RTZ reset button for 3 seconds, and the screen display will reset. 3. USB intelligently monitors power and capacity. 4. Portability: This product is small in size, light in weight, and convenient to carry. 5. Good Quality: This product is made of high-quality materials, exquisite workmanship, good quality, and long service life. It can also assist with safe charging and monitor your charging data in real-time. Model: KWS-V21 Input/Output: 4-20V, Resolution: 0.01V Current: Input/Output Current: 0-3A, Current Resolution: 0.01A Temperature: 60 (°C) Accuracy: 1% Line Loss: approx. 0.1 ohm Color: 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 screens may cause the color of the item in the picture to differ slightly from the real thing. The allowed measurement error margin is +/- 1-3 cm.