Arduino Pro Micro - Small Low Cost Versatile Board

Description Features Documents It's blue! It's thin! It's the Arduino Pro Mini! SparkFun's minimal design approach to Arduino. This is a 3.3V Arduino

Arduino Pro Mini 328 - 3.3V/8MHz

Don't gettit Pro Micro question 5V or 3,3V?? - Microcontrollers - Arduino Forum

running at 5V/16MHz Supported under IDE v1.0.1 On-Board micro-USB connector for programming 4 x 10-bit ADC pins 12 x Digital I/Os

OSOYOO Pro Micro 5V/16MHz Module Board with 2 Row pin Header Replace wit Pro Mini for Arduino

SparkFun Arduino Pro Mini ATmega328 - 3.3V/8MHz Development Board Incl 8 Analog Pins and 14

PD Micro

D1 Mini Proarduino Leonardo Board With Usb Interface - 5v/16mhz, 3.3v/8mhz, 2-row Pin Header

The Micro is a microcontroller board based on the ATmega32U4, developed in conjunction with Adafruit. It has 20 digital input/output pins (of which 7 can be used as PWM outputs and 12 as analog inputs), a 16 MHz crystal oscillator, a micro USB connection, an ICSP header, and a reset button. It contains everything needed to support the microcontroller; simply connect it to a computer with a micro USB cable to get started. It has a form factor that enables it to be easily placed on a breadboard.