Adafruit Metro 328 without Headers
ATmega328 microcontroller with Optiboot (UNO) Bootloader
USB Programming and debugging via the well-supported genuine FTDI FT231X
Input voltage: 7-9V (a 9VDC power supply is recommended)
5V logic with 3.3V compatible inputs, can be converted to 3.3V logic operation
20 Digital I/O Pins: 6 are also PWM outputs and 6 are also Analog Inputs
6-pin ICSP Header for reprogramming
32KB Flash Memory - 0.5K for bootloader, 31.5KB available after bootloading
16MHz Clock Speed
Compatible with "Classic" and "R3" Shields
Adafruit Black PCB with gold plate on pads
53mm x 68.5mm / 2.1" x 2.7"
Height (w/ barrel jack): 13mm / 0.5"
Derivative of "Arduino UNO R3 Reference design"