The Pro Micro is an Arduino compatible microcontroller board. It has an AVR ATmega32u4 8-bit microcontroller which has an integrated USB controller. It has a micro-USB type B port, 18 I/O pins and an integrated voltage regulator for 3V operation. This is the 5V 16Mhz version. Pin headers included. USB cable not included.
Find out more, including the pinout diagrams here on Deskthority.