Poweradd SLIM2 ™ 5000mAh Portable Charger External Battery Backup for iPhone 5S 5C 6 5 4 4S, iPod (Apple Adapters Not Included) Samsung Galaxy S5 S4 S3 S2, Note 2, Note 3, HTC One (M8), and Android Smart Phones Other Devices Charged Via USB 5V-Black (that is the best gift for your friend) (Electronics)
Unsurprisingly, the battery works well: it takes care of a USB port, or using the charger for your smartphone, and then it can charge any USB-powered device: smartphone, tablet, GoPro GPS. .. and as it provides an output voltage of 2.1 ampere, it off