Check the listing for details. ATmega32U4 Pro Micro Controller for Arduino Micro USB 5V 16MHz Replace ATmega328. Condition: New. Listed at 6.95 USD. This tiny little board does all of the Arduino tricks that you're familiar with: 4 channels of 10-bit ADC, 5 PWM pins, 12 DIOs as well as hardware serial connections Rx and Tx. Running at 16MHz and 5V, this board will remind you a lot of your other favorite Arduino-compatible boards but this little guy can go just about anywhere. 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 on not VCC. Features: ATMega 32U4 running at 5V/16MHzSupported under Arduino IDE v1.0.1On-Board micro-USB connector for programming4 x 10-bit ADC pins12 x Digital I/Os (5 are PWM capable)Rx and Tx Hardware Serial Connections Package: 1 X New Pro Micro ATmega32U4 5V 16MHz Module