Features:1. The runtime and capacity display has a memory function when power off.2. Press the RTZ reset button for 3 seconds and the display screen will be reset.3. USB intelligently monitors current and voltage.4. Portability: This product is small, lightweight, and very convenient to carry.5. Good Quality: This product is made of high quality materials, exquisite workmanship, very good quality and long service life. Description:It can also help you charge safely and monitor the charging data in real time. Specifications:Model: KWS-V21 Measuring Range: 4-20 (V)Input Voltage: 4-20 (V)Output Voltage: 4-20 (V)Ambient Temperature: 60 (°C)Dimensions: 59*23 (mm)Voltage Measurement Error: 1-2%Package Included:1 * USB Current Current Voltage Capacitance TesterNotes:1. Please allow 0-1 inch error due to manual measurement. Thank you for your understanding.2. Monitors are not calibrated same, item color displayed in photos may be showing slightly different from the real object.