This is the new Arduino Uno R3. In addition to all the features of the previous board, the Uno now uses an ATmega16U2 instead of the 8U2 found on the Uno (or the FTDI found on previous generations). This allows for faster transfer rates and more memory.
This is a Double-Side PCB Circuit Board, Each PCB board has 8 pins, It is compatible with 4 pins 6 pins and 8 pins chips.