It’s blue! It’s thin! It’s the Pro Mini! This is a 5V board running the 16MHz bootloader. Pro Mini 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 users start with the Arduino® Uno R3. It’s a great board that will get you up and running quickly. The Pro series is meant for users that understand the limitations of system voltage (5V), lack of connectors, and USB off board.
Pro Mini is made with all SMD components on two layers of PCB. This board connects directly to the FTDI Basic Breakout board and supports auto-reset. The Pro Mini 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. There is a voltage regulator on board so it can accept voltage up to 12VDC. If you’re supplying unregulated power to the board, be sure to connect to the “RAW” pin and not VCC.