The Arduino Micro (without headers) is a microcontroller board based on the ATmega32u4, developed in conjunction with Adafruit. It contains everything needed to support the microcontroller, simply connect it to a computer with a micro USB cable to get started. It has a form factor that enables it to be easily placed on a breadboard.

Specifications:

-Microcontroller: ATmega32u4
-Operating Voltage: 5V
-Input Voltage (recommended): 7-12V
-Input Voltage (limits): 6-20V
-Digital I/O Pins: 20
-PWM Channels: 7
-Analog Input Channels: 12
-DC Current per I/O Pin: 40 mA
-DC Current for 3.3V Pin: 50 mA
-Flash Memory: 32 KB (ATmega32u4) of which 4 KB used by bootloader
-SRAM: 2.5 KB (ATmega32u4)
-EEPROM: 1 KB (ATmega32u4)
-Clock Speed: 16 MHz