Description:
The UNO is a microcontroller board based on the ATmega328P. It has 14 digital input/output pins (6 of which can be used as PWM outputs), 6 analogue inputs, a 16 MHZ quartz crystal, a USB connection, a power jack, an ICSP header, and a reset button. It contains everything needed to support the microcontroller, simply connect it to a computer with the supplied USB cable or power it with an AC to DC adapter or battery power to get started.

This board is the ATMega16U2 version.

Specifications:
Microcontroller: ATmega328P
ATMega16U2
Operating Voltage: 5V
Input Voltage (recommended): 7 – 12V
Digital I/O Pins: 14 (of which 6 provide PWM output)
PWM Digital I/O Pins: 6
Analog Input Pins: 6
DC Current per I/O Pin: 20mA
DC Current for 3.3V Pin: 50mA
Flash Memory: 32KB (ATmega328P) of which 0.5KB used by the bootloader
SRAM: 2KB (ATmega328P)
EEPROM: 1KB (ATmega328P)
Clock Speed: 16 MHz
Built-in LED: 13
Length: 68.6mm
Width: 53.4mm
Weight: 25g
 
Package includes: 
1 Arduino Uno