GRUCORE 18650 Battery Charger Slim 3A USB 2 Ports LCD Indicator Power Bank, 3 Bay DIY your power bank. GRUCORE is not only a external battery/power bank, but also a charger for 18650 batteries. You can use 1-3 batteries or charge 1-3 batteries at will. (Battery is NOT included) High Expand Capacity: Use 3pcs 3400mah batteries can get nearly 10000mAh of power. Enough to provide 2-3 charges to an iPhone 7 and Galaxy S7. Double USB ports of 1A/2A can charge cellphone and tablet PC at the same time. The intelligent identifying IC will provide the most suitable current output for your devices. Built in overcharge protection, short circuit protection. No worry of damage power bank by putting batteries in wrong direction. Ultra-Compact: 3.9 inch tall and 2.5 inch wide portable design slides easily next to your phone in any pocket or bag. Smaller than a iPhone 6/6s