DROK USB 2.0 Charger Detector Voltage Ampere Meter Digital USB 2.0 Voltmeter Ammeter Volt Amp 2 in 1 Multimeter Current Voltage Reader with Red&Blue Dual LED Display for Charging iPhone iPad Test voltage and current of charging or discharging in real time. Great to choose safe and suitable current to charge your cell phone and ipad. Output I for original charger, output II is for both original and non original charger. With protective function, over&low volt protection/over current protection/short circuit protection.