2. Increased needle socket, convenient you use dupont line.
3. Please note that Replace the 16u2, make the cost reduced to half, consumers obtain maximum benefits
Arduino project launched using ATMEGA8U2, ATMEGA16U2 version of the product is have their own ideas, in the vast majority of applications, the USB interface chip only as a serial port and communication of "flash". With professional and the usb chip, not only can reduce the cost, and good application