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 Adrian Smart

I have used other 4 channel relays with my Raspberry Pi before but none of these mount directly to the Pi. This format eliminates the jumpers between the Pi and the relay board. I love that the board comes with gaskets, nuts and bolts to attach it to the Pi and protect the GPIO pins on the Pi from unnecessary pressure or adjustments. As a previous reviewer said, my only complaint is that you don't have access to the unused GPIO pins on the Pi board (although you can connect to exposed solder pads on the relay board).