Review on Keyestudio 5V DCAC 4-Channel Relay Hat Shield Module Expansion Board for Raspberry Pi 4, A+, B+, Pi 2 Model B, Pi 3 Model B by Jennifer Norris

I wanted to leave a review here because I've read a number of reviews that were dissatisfied at the documentation level. In fact there is no documentation on the box, just a relay module. However, I saw a QR code on the back of the box, so I scanned it and opened the website it pointed to. Not only did this give me all the documentation I could want, it also gave me code examples and links to places to download more! I just used the basic sample code from the website and (after installing the "wiredPi" library) compiled it and it worked the first time! My project is currently working fine with this relay. Will definitely order again if I need another 4 relay module.