The Arduino Pro Mini is a microcontroller board based on the ATmega328. 
It has 14 digital input/output pins (of which 6 can be used as PWM outputs), 6 analog inputs, an on-board resonator, a reset button, and holes for mounting pin headers. A six pin header can be connected to an FTDI cable or Sparkfun breakout board to provide USB power and communication to the board.
The Arduino Pro Mini is intended for semi-permanent installation in objects or exhibitions. The board comes without pre-mounted headers, allowing the use of various types of connectors or direct soldering of wires. The pin layout is compatible with the Arduino Mini. 
There are two version of the Pro Mini. One runs at 3.3V and 8 MHz, the other at 5V and 16 MHz. 

• Microcontroller ATmega328 *

• Board Power Supply : 5 - 10 V (5V model)

• Circuit Operating Voltage : 5V

• Digital I/O Pins 14

• PWM Pins 6

• UART 1

• SPI 1

• I2C 1

• Analog Input Pins 6

• External Interrupts 2

• DC Current per I/O Pin 40 mA

• Flash Memory 32KB of which 2 KB used by bootloader *

• SRAM 2 KB *

• EEPROM 1 KB *

• Clock Speed 16 MHz (5V versions)