Rogue Wireless Fast Charge 2200 mAh USB PowerBank

Got 2, each came w/ their own UK adapter plug and it charged at the wall quite fast. Unplugged it, attached the phone cord to its port, pressed the round, white power button and it’s charging my S3. Nearly as fast as if the phone was charging at the wall.

What is the power amp output? 1 or 2 or 2.4 etc for USB charging?