What is an UNO R3 (Arduino Compatible) Board?

ZYLtech ATmega328P ATMEGA16U2 Compatible with UNO R3 for Arduino w/ USB Cable - ZYLtech Engineering, LLC

Arduino UNO Compatible Board ATmega328

Uno R3 with ATmega16U2 USB - ProtoSupplies

100% compatible with the Arduino IDE. The ELEGOO UNO R3 controller board now uses a CH340C chip and SMD ATmega328p chip (same as Arduino UNO R3), with

ELEGOO UNO R3 Controller Board ATmega328P with USB Cable, Compatible with Arduino IDE

An overview of different UNO boards – Arduino Help Center

Arduino (Compatible) UNO R3 with usb cable - Maker Store USA

UNO R3 Development Board ATMEGA328P Chip CH340G yellow micro-USB (Compatible with Arduino Uno)

XiaoR GEEK Arduino UNO R3 main board with driver expansion board kits

2 units-Compatible with Arduino UNO R3 IDE, ATmega 328P CH340 Development Board

ELEGOO Uno Project Super Starter Kit with Tutorial and Uno R3 Compatible with Arduino