Features: The KWSV21 USB Power Tester precisely measure voltages (4-20V±1%) and current (0-3.3A) with 0.01resolution, featuring a reset button for screen clearings and memory retention after power loss. Equipped with input/output voltages/current indicators, this USB voltmeter ammeter combines 0.01V/A resolution with ±1%accuracy for reliable mobile power analysis. Ideal for electronics technicians, DIY enthusiasts, and repair specialists needing to verifys charger outputs or diagnose USB cable/portable battery issue. Perfect for testing wall charger, car adapters, and powerbanks in home labs, workshops, or during mobile device troubleshooting. Its compactly ABS construction and quick charger compatibility (up to 20V) make this essential tester tool user friendly for daily USB device performances monitoring. Specifications: Component:ABS Length:Approx.7.22cm/2.84inch Display Type: Digital Only Input/Output voltages:4 -20V Input/Output current: 0-3.3A Accuracy:±1% Package Includes: 1pc USB Voltmeter note: Please allow 1-2cm errors due to manual measurement. Due to the differences between different monitors, the picture may not reflect the actual item color.