【RESET BUTTON DESIGN】: USB power tester has designed with reset button, and you can press 3-5 seconds to the screen cleared, and this USB Voltmeter Ammeter can bring you good using experience. 【REAL-TIME TESTING】: USB power tester can measure USB charging voltage, current and discharge capacity over time, which is brand new and has high quality assurance. 【MEMORY FUNCTION】: USB power tester support empty display with memory function after power off, and the power tester can be used to check the performance of USB cables, wall chargers, car chargers and power banks. 【FAST CHARGER AVALIABLE】: USB power tester is compatible with fast-charger, which can work under up to 20V, and the power tester does not interfere with fast charge negotiation, will be good helper to you. 【AFTER SALE SERVICE】: If you have any questions about this USB power tester, please feel free to contact us immediately,and we will serve you wholeheartedly.