Arduino-Pro Mini is a small, thin Atmega328P microcontroller based minimum system board designed by sparkfun as an minimum system Arduino. This Pro mini improved version runs at 16MHz speed with 5V supply. Arduino pro mini comes with connectors which are not soldered in to the board which gives you freedom to solder them as you like. This pro mini board is intended to use by advanced user who knows how to upload a code without the on board usb chip. it can be programmed by Arduino IDE with the help of any USB to TTL board by connecting RX-TX lines, board has regulator which can take 9-12 volts at RAW pin, VCC pin is intended to take regulated 5V as input. It has 6 pin header connector for programming, 14 digital IO lines, 8 analog lines, on board 16 MHz crystal, reset button, Pro mini A4 and A5 pins are hardware SDA, SCL lines for using I2C. All the headers are included with this small board.