for iphone 4G battery case
1.backup battery for iphone
2.Battery combined case
3.On/Off Switch
4.Color: red black white

for iphone 4G battery case 

Features:

Re-Charging
You can use the included USB cable to charge the external battery and iPhone
simultaneously or charge the external battery on its own via the built-in USB port of the external battery.

Light LED Battery Status Indicator
The integrated LED status indicator tells you exactly how much juice is left in your
external battery. Simply press the Test button(on the left next to the LED indicator) and it will tell you how much power is left.
The LED lights also indicate the charging status and charging progress.

On/Off Switch
Use the external battery when you need it. The built-in on/off switch(located at the bottomo of the external battery) allows
you to use the external battery just as a case or as a battery at the flick of a switch.

Pass-through USB
Charge and sync your iPhone to iTunes without removing it from the external battery.

Battery and Case in One
Offers the convenience of an extended battery and the full protection of a hardshell case.
Use it as a case all the time or just when your iPhone needs an extra boost.

Powerful and Safe Battery Cell
Built in overcharge, short-circuit and temperature protection. Latest in lithium
polymer battery technology offers the most power and thinnest and lightest form factor.

Technical Specification:

Battery:         lithium polymer battery

Material:        polycarbonate

Capacity:             1900mAh 

Input:                    DC5V/500mA
Charging time:    4 hours
Standby time:      Up to 360 hours
Talk time:             Up to 6hours on 3G
                               Up to 13.3hours on 2G
Internet Use:        Up to 6 hours on 3G
                               Up to 10.6 hours on Wi-Fi
Audio play:            Up to 36hours
Video play:            Up to 10.6 hours