Arduino Pro Micro is another Arduino Compatible breadboard friendly board designed by spaarkfun. Pro micro made of Atmega32U4 single USB chip with 32K flash for user programming. It operates at 5V and 16MHz frequency is generated by crystal onboard. This small board has double row pin header with 4 channel 10-bit ADC, 5 PWM Pins, 12 Digital IO as well as hardware serial RX and TX. Running at 16MHz and 5V. There is a voltage regulator on board which can accept 12 VDC. If you are supplying unregulated power to the board make sure it should connect to RAW pin not VCC pin. You can use Arduino IDE to program this board by selecting Pro Micro.