The BeGrit UNO R3 Development Board 100% New & High Quality
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 with both the board that uses the AVR, which operates with 5V and with the Arduino Due that operates 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. ATmega16U2 offers Arduino UNO R3 the ability to show up as a variety of USB devices - keyboard, mouse, joystick, MIDI etc.
A microcontroller board based on the ATmega328 (datasheet)
It contains everything needed to support the microcontroller
Simply connect it to a computer with a USB cable or power it with a AC-to-DC adapter or battery to get started
Added SDA and SCL pins that are near to the AREF pin
The RESET circuit is more stable
Atmega 16U2 replace the 8U2
Size: 75 x 53 x 10mm/ 2.95 x 2.09 x 0.39in

• Simply connect it to a computer with a USB cable or power it with a AC-to-DC adapter or battery to get started
• Atmega 16U2 replace the 8U2. ATmega16U2 offers Arduino UNO R3 the ability to show up as a variety of USB devices - keyboard, mouse, joystick, MIDI etc
• Added SDA and SCL pins that are near to the AREF pin
• The RESET circuit is more stable
• It contains everything needed to support the microcontroller

Simply connect it to a computer with a USB cable or power it with a AC-to-DC adapter or battery to get startedBeGrit