1. replace the 2011 version of ATMEGA8U2 with ATMEGA16U2 chip, ISP FLASH capacity doubled to facilitate more powerful function expansion, development needs. ATMEGA16U2 in addition to providing the USB to serial port function, also allows users to their own definition of other functions, such as the USB port can be configured as a mouse, keyboard, game Of course, these applications are still for the duino team to the implementation plan. 2. external interface in the 2011 version based on the addition of SDA, SCL (positioned on the left side of AREF). ioref interface can a voltage reference to . And in order to series compatibility considerations IOREF left reserved a port. 3. RESET circuitry has been improved over the 2011 version. Prevent RESET accidental reset, RESET circuit is more stable. Colour:As shown :PCB Package Contents: 1 x Development Board Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.