Global tesco Universal USB Voltmeter Ammeter Power Meter Tester Multimeter, Test Speed of Chargers, Cables, Capacity of Power Banks Precise current calibration to provide accurate test. Input Voltage: 3-7V, Input Current: &lt;3.5A, Capacity: 0-19999mAh. Easy to read data on LCD display both day and night. Test using a USB charger, battery power bank or Micro USB Cable. Test your iPhone or Android phone Store charging data in memory. Flashes to alert of low or high voltage issues.