TeckNet Zenith Z1 13000mAh USB External Battery Pack Power Bank with BLUETEK&trade; Smart Charging Technology, Mobile Phone Power Pack, High Capacity Portable Battery Charger for USB Devices Features cutting-edgeBLUETEK&trade; Technology which identifies and optimises USB power compatibility of devices from Apple, Samsung and many other devices to enable faster recharge rates of up to 3.1A. Massive13000mAh capacity recharges an iPhone 5s almost 5-6 times, a Galaxy S5 over 4 times or one full recharge for iPad Air. Unrivalled 93% charging efficiency -5-10% more than other brands. Includes an auto-off function. Samsung Grade A battery cells and premium chips ensure reliability and safety Duo-Charge function enables charging of the Powerbank while it recharges a connected device such as an iPhone. 2A input for super quick recharging, saves up to 25%-50% charge-time compared to other battery brands. 4 LEDs displays to show just how much juice you've got left. Integrated fuses and thermal protection design.