SainSmart Mega2560 R3:

*1.0 pinout: added SDA and SCL pins that are near to the AREF pin and two other new pins placed near to the RESET pin, the IOREF that allow the shields to adapt to the voltage provided from the board. In future, shields will be compatible both with the board that use the AVR, which operate with 5V and with the Arduino Due that operate with 3.3V. The second one is a not connected pin, that is reserved for future purposes.
*Stronger RESET circuit.
*Atmega 16U2 replace the 8U2

The SainSmart Arduino XBee board for Arduino:

It mates directly with the Arduino USB board and allows to wireless communicate over a modified ZigBee protocol using the popular XBee module from Maxstream.

The module is easy to use, low power consumption, and the provision of critical data between devices reliable transmission. As the innovative design, XBee-PRO can be in the range 2-3 times beyond the standard ZigBee modules. XBee-PRO modules work in the ISM 2.4 GHz frequency band. The MaxStream's XBee (1 mW) Zigbee module is pin-compatible.You can use a simple AT command to advanced configuration. An OEM developer is now XBee code development package. It is self-developed in collaboration with the MaxStream ZigBee/802.15.4 RF module code.

Package list:

• 1 SainSmart Mega 2560
• 1 SainSmart XBee Shield