• The goal of the Pro Mini isn't to replace the Arduino so much as bring the cost down for more advanced users.  The Arduino Uno is still the inimitable board but if you're comfortable working within voltage limitations, don't mind off-board USB, and want to customize your connectors, the Arduino Pro Mini's a great budget purchase. You will need an FTDI friend to program your Pro Mini, and we also recommend some plain header to solder it for breadboard use
• Note that the FTDI port on the Pro Mini 3.3V expects both 3.3V power and data/logic! You will need to adapt the FTDI programming interface to make sure it is both 3V logic and power
• Check out SparkFun's tutorial for more info on how to get started with the Arduino Pro Mini!
• If you would like an Arduino IDE compatible board with USB, also check out the Pro Trinket 3.3V!

• Dimensions w/ Components: 33mm x 18mm x 2mm / 1.3" x 0.7" x 0.1"
• 3.3V regulator
• Max 150mA output
• DC input 3.3V up to 12V
• 8 Analog Pins
• 14 Digital I/Os

Documentation:

• Schematic

Package Includes:

• 1 x Adafruit 2377 Arduino Pro Mini 328 - 3.3V/8MHz