Review on 🎄 Onyehn 2pcs/Lots MAX7219 Dot Matrix Module (Red Light) 4 in 1 Display: Christmas Decoration DIY Letters Electronic Display for Arduino Microcontroller with 5Pin Line by Scott Chen

I used them for a small Arduino alarm clock project. The screens work great, they're easy to get up and running, and placing them behind tinted glass makes the effect even better. They draw a lot of current when on at full brightness, so I recommend connecting the 5V power supply directly to the shields - so they don't draw everything from the Arduino's USB port and at least a 2A power supply that gets hot will. . Since this project will keep the screens working all the time, I'll update the review when they start to fail.