Displays Current (Amps)， voltage and capacity (19，999 mah)Perfect for testing how fast a USB cable or USB power adapter charger is actually charging atCan handle charging speeds up to 3.5A (3，500 ma) and 3v-7vStore charging data in memory. Flashes to alert of low or high voltage issuesTest using a USB charger， battery power bank or Micro USB Cable. Test your iPhone or Android phone