It's thin! It's blue! It's the Arduino Pro Micro! The?Pro Micro?is similar to the?Pro?Mini except with an ATmega32U4 on board. This is also 5V 16MHz dev board.
Thinary Electronic Pro Micro ATmega32U4 5V/16MHz Module
5V Pro Micro Type-C USB ATmega32U4 Development Board for Arduino
Great little Arduino compatible board.Arduino Leonardo based, well built, up and running with a test sketch in minutes.One bonus to the 32U or
Ardest Pro Micro for Arduino Leonardo Chromebook Deployments ATmega32U4 5V/16MHz Module Board with 2 Row pin Header Replace ATmega328 Arduino Pro
Pro Micro Leonardo - 5V/16MHz
Pro Micro 5V 16M Mini Leonardo Microcontroller Development Board For A
Arduino Pro Micro ATmega32U4 5V/16MHz – Electroslab
Buy Mini USB ATmega32U4 Pro Micro 5V 16M Microcontroller
Pro Micro 5V / 16MHz - ProtoSupplies
KEYESTUDIO 5V Pro Micro Atmega32U4 with USB Cable for Arduino
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GY Pro Micro 5v / 16M Mini Microcontroller Development Board Nano Module
Pro Micro 5V 16M Mini Leonardo Microcontroller Development Board For A
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
Microcontroller Arduino Compatible Pro Mini - shop.