AITRIP 4pack Pro Micro ATmega32U4 5V/16MHz Module Board with 2 Row pin Header for arduino Leonardo Replace ATmega328 Pro… Price: $18.99 (as of 24/11/2020 03:22 PST- Details)

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ATmega32U4 running at 5V/16MHz; Supported under Arduino IDE v1.0.1
4 x 10-bit ADC pins, 12 x Digital I/Os;Rx and Tx Hardware Serial Connections