Add 13 digital output pins to your Arduino! This shield has 16 digital output pins and only “uses” 3 of your existing pins to operate (8, 12, and 13). When placed on top of an Arduino board, it only covers half of the Arduino. The new digital outputs are pins numbered 20-35. The EZ-Expander software library makes it very easy to access the new output pins. This product is fully assembled and tested.
EZ-Expander Shield page: all the details about this shield and the software library