KWSV21 USB Power Tester Precise measurements: measures voltages from 4 to 20 V with ±1% accuracy and currents from 0 to 3.3 A, with a resolution of 0.01 V for voltage and 0.01 A for current. Screen control and memory: includes a reset button to clear the display, and the unit retains memory after power loss for convenient review. Clear indicators: input and output voltage/current indicators provide ataglance readings for quick mobile power analysis. Reliable performance: designed for accurate and dependable charging analysis with consistent 0.01 V / 0.01 A resolution and ±1% accuracy. Target users: ideal for electronics technicians, enthusiasts, and specialists who need to verify charging outputs or diagnose USB cables and portable batteries. Practical use scenarios: Test wall chargers and car adapters to confirm they deliver expected voltage and current. Check power banks and USB cables to identify degraded performance or faults. Use during mobile device troubleshooting in home labs, workshops, or onsite.