1900mA External universal portable power bank case For Iphone 4 4S 

Specifications: 
Product item
backup case battery for iphone 4/4s 
Weight: 65g 
Capacity: 1900mAh 
Cell type: Li polymer battery Lithium-ion 
Dimension: 12.5X63X16mm 
Output voltage 5V 
Output current 500mA 
Cycle life 500 times 
Function & character: 
1.Enhance iPhone4 signal 
2.Power check & indication 
3.Power switch 
4.Protective and powerful 
Signature: 
Standby time up to 230 hours 
Talk time up to 5.5 hours on 3G& 
up to 8 hours on Wifi 
Audio Playback up to 30 hours 
Video Playback up to 8 hours