Controllled by Serial or the I2C Interface. 
Two modes of operation, direct individual control of the motors or the ability to send a speed and a turn commands. 

Full MD25 Documentation

Voltage - 12v only. The 5v for the logic supplied from an on-board regulator, 300mA available for your own circuits. 
Current - Up to 2.8A for each motor. 
Encoder - Processes quadrature encoder inputs from motor. 360 counts per wheel turn when used with the EMG30.
Size - 110mm x 52mm x 25mm