Atmel ATMEGA328P -U AVR preloaded with Arduino UNO bootloader +16Mhz +2x 22pF
Two 22pF disc capacitors. one 16Mhz crystal (hc-49s). Preloaded with ARDUINO UNO bootloader. (PicoPower version, 32KB Flash, 8 bit). Resources that you may find useful:(copy into a new browser window).