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 Jerry Delic

I have used this relay to build a sofa automation. This PI hat made the job a lot easier than expected. It runs on GPIO pins, so just use the pin library and apply power. Everything is easy. My only complaint is that the leftmost connector of the leftmost relay and the rightmost connector of the rightmost relay are partially covered by the board standoffs. This isn't a problem for me, but make sure you have some flex in your harness to maneuver these obstacles.