Credit card power bank, slim size portable battery pack with 2500mAh capacity. Elegant and beautiful appearance. With advanced A-grade high-energy polymer lithium-ion battery cells.Add 18 hours for I Phone movie playing time. Built-in battery tester button with managing battery level and charging LED indicator. With internal protection functions for short circuit, overcharge and over temperature. One key combination of Power key and capacity indicator.Built-in cable credit card power bank. Once 10 seconds without work, the device will go to automatically power off. Four levels power indication. Best credit card power bank.