2500mah Best Iphone 5/5s Battery Case Rechargeable External Power Backup Charger Case (Black) 1. Capacity: 2500mAh for iphone 5/5s backup power; Ergonomic, form-fitting,fully protective impact-resistant case-and-battery in one for iPhone; 2. Integrated power switch allows you to put the External Battery Case in standby model. Only use the battery when you need it. In standby mode(red), the External Battery Case still allows charge and sync capabilities through the micro-USB port and still offers the complete protection of case; 3. User breakthrough rechargeable lithium polymer battery. (Much safer than those troublesome lithium Ion batteries); 4. State-of-the-art battery technology extends the life of your Iphone for hours.....and you can even recharge it while it's still connected to the Iphone! This battery rocks 5. Smart battery technology actually instructs the Iphone to drain out the External Battery Case. When you're done with the External Battery Case, you can pull it off and still have a fully charged iphone.