Pro Micro Arduino Compatible 16MHz or 8MHz - Canada

KOOKYE 3pcs Pro Micro ATmega32U4 5V/16MHz Module Board with 2 Row Pin Header for Arduino Leonardo Replace ATmega328 Arduino Pro Mini

Pro Micro (Micro-USB) - 5V/16MHz - Arduino-compatible ATmega32U4 – Keebio

Pro Micro 5V / 16MHz - ProtoSupplies

QMK Proton C pre-sales (16 USD) starting now! Multiple stores, raffle for the samples, and other news in the comments : r/olkb

Arduino Pro Mini 328 - 5V/16MHz - RobotShop

Pro Mini ATmega328P 5V - 16MHz (100% Compatible With Arduino IDE)

Mini ATMEGA328 ATMEGA328P ATMEGA328 Module 3.3V 8MHz Development Board Electronic Building Block for Arduino Development Board

3.3V/5V 8/16MHz Pro Micro ATMEGA32U4 USB Controller Board Bootloader for Arduino

Pro Mini 3.3V / 8MHz Arduino Compatible Microcontroller - RobotShop