Here at SparkFun, we refuse to leave 'good enough' alone. That's why we're adding to our line-up of Arduino-compatible microcontrollers once more! The Pro Micro is similar to the Pro Mini except with an ATmega32U4 on board. The USB transceiver inside the 32U4 allows us to add USB connectivity on-board and do away with bulky external USB interface. Project description, more information and ordering can be found at https://www.sparkfun.com/products/11098 Getting Started Tutorial: http://www.sparkfun.com/tutorials/338 Datasheet: http://dlnmh9ip6v2uc.cloudfront.net/datasheets/Dev/Arduino/Boards/ATMega32U4.pdf Pro Micro Add-on: http://dlnmh9ip6v2uc.cloudfront.net/datasheets/Dev/Arduino/Boards/SF32u4_boards.zip Firmware Note: https://dlnmh9ip6v2uc.cloudfront.net/datasheets/Dev/Arduino/Boards/32U4Note.pdf