This is version 2.3 of the Mega IO Expansion shield. This shield is extra large and includes 3 Xbee slots, 1 microSD slot, Arduino shield headers to plugin most Arduino shields. It also includes a prototyping area and breakouts for Digital pins 14 to 53, Analog pins 6 to 15 and PWM pins 2 to 9. This shield can be a major communications hub for your projects.
Specifications
support most of the arduino shield
compatible with the Arduino Mega boards/DFRobot ADK/Arduino ADK
Extended TTL connection pins for four Serial ports
DIP prototyping area makes it easy to add more chips or electronic components
3 Xbee slots
1 microSD slot
power selector to select between Arduino Mega power or external power