This shield is used to provide a rechargable battery pack for the Arduino.

 The mini-USB port is used to charge the Li-ion or Lo-ion poly battery (NOT INCLUDED). There are LEDs showing the charging, full status.

 6 big mounting holes can help you easily fix the battery pack.

For a 600mAH battery, it takes about half hour to charge.

Document:

  Data sheet of the charging IC

  Schematics