Arduino Pro Mini Compatible ATmega32U4 5V/16MHz -AR-139-D
Its blue! Its skinny! Its the Arduino Pro! Campus component minimal design approach to Arduino. This is a 5V Arduino running the 16MHz bootloader (select Arduino Duemilanove w/ 328 within the Arduino software). The power switch was moved to the side of the board (good idea Limor!) to allow control when a shield is attached.
Arduino Pro Mini Compatible does not come with connectors populated so that you can solder in any connector or wire with any orientation you need. We recommend first time Arduino users start with the Duemilanove. Its a great board that will get you up and running quickly. The Arduino Pro series is meant for advanced users that understand the limitations of system voltage (5V), lack of connectors, and USB off board.
Campus Component really wanted to minimize the cost of an Arduino. The Arduino Pro is like the Arduino Duemilanove (same pin out) but to keep the cost low, they used all SMD components, made it two layer, etc. This board connects directly to the FTDI Basic Breakout board and supports auto-reset. The Arduino Pro also works with the FTDI cable but the FTDI cable does not bring out the DTR pin so the auto-reset feature will not work.