Fixing an Arduino Pro Micro: the USB Port Came Off !! : 17 Steps - Instructables
Alternatives · joric/nrfmicro Wiki · GitHub
Amazon.com: RedTagCanada Pro Micro Atmega32U4 5V 16MHz Bootloadered IDE Micro USB Pro Micro Board Microcontroller Compatible to Arduino Pro Micro Serial Connection wPin Header (1, Pro Micro ATmega32U4 Micro-USB) : Electronics