The Mega 2560 R3 is an open source precise microcontroller board Successor to the Mega based on the ATmega2560 SMD chip.The Mega 2560 R3 also adds SDA and SCL pins next to the AREF. In addition, there are two new pins placed near the RESET pin. One is the IOREF that allow the shields to adapt to the voltage provided from the board. The other is a not connected and is reserved for future purposes. The Mega 2560 R3 works with all existing shields but can adapt to new shields which use these additional pins.

Specifications:
Microcontroller: ATmega2560
Operating Voltage: 5V
Input Voltage (recommended): 7-12V
Input Voltage (limits): 6-20V
Digital I/O Pins: 54 (of which 15 provide PWM output)
Analog Input Pins: 16
DC Current per I/O Pin: 40 mA
DC Current for 3.3V Pin: 50 mA
Flash Memory: 256 KB of which 8 KB used by bootloader
SRAM: 8 KB
EEPROM: 4 KB
Clock Speed: 16 MHz
USB Host Chip: MAX3421E
Length:101.98mm/4.01in
Width:53.63mm/2.11in
Height:15.29mm/0.60in

Packing Included :
1 x Mega 2560 CH340 Microcontroller
1 x Cable