It's a Bluetooth board for the Paper-Duino-Uno or the Duino-Mini. It's based on the Bluetooth Module RS232/TTL HC-05. It is a Master and Slave integrated Bluetooth serial module:

The default setting for the serial port is: 9600, N, 8,1 and the password is: 1234.
There are two versions, one for the Paperduino-UNO and one for the Paper-Duino-Mini. For the UNO board on has to modifier the power jumper that the Blutooth board is powered over the external power.
Front:

Back:

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