These are very slim, extremely light weight batteries based on the new Polymer Lithium Ion chemistry. This is the highest energy density currently in production. Each cell outputs a nominal 3.7V at 2000mAh! This battery comes terminated with a standard 2-pin JST connector - 2mm spacing between pins. Do not attempt to charge these with anything but a charger specifically designed for LiPo batteries.

Battery includes built-in protection against over voltage, over current, and minimum voltage. 

Note: Be careful with the JST connectors. They can stick in pretty good and tugging on them can damage the connector. Check this tutorial for an easy way to remove them safely.

• Dimensions: 54.5 x 61.5 x 6.5 mm
• Weight: 41g
• Capacity: 2000mAh
• Max Continuous Discharge Current: 4000mAh (2C)
• Robust power source under extreme conditions (-20 to 60C)

• Datasheet
• JST connector