1、Support for Arduino IDE 1.0+ (for OSX/Win/Linux). 2、Power via USB or External Source - 5V or 7-35V (12V or less recommended, automatic selection). 3、On-board 500ma 5V Regulator. 4、6 I/O Pins (2 are used for USB only if your program actively communicates over USB, otherwise you can use all 6 even if you are programming via USB). 5、8k Flash Memory (about 6k after bootloader). Features: 1. Support for Arduino IDE 1.0+ (for OSX/Win/Linux). 2. Power via USB or External Source - 5V or 7-35V (12V or less recommended, automatic selection). 3. On-board 500ma 5V Regulator. 4. Built-in USB. 5. 6 I/O Pins (2 are used for USB only if your program actively communicates over USB, otherwise you can use all 6 even if you are programming via USB). 6. 8k Flash Memory (about 6k after bootloader). 7. I2C and SPI (vis USI). 8. PWM on 3 pins (more possible with Software PWM). 9. ADC on 4 pins. 10. Power LED and Test/Status LED. Specification: Size: about 2*1.7cm/0.79*0.67inch Package Size: about 8*6*1cm/3.15*2.36*0.39inch Material: ABS Package List: 1 * Module