3-CH RPi Relay Board RPi Expansion Board, Three Channel Power Relay Module Compatible with Raspberry Pi 5/4B/3B+/3B/Pi Zero W/Zero 2W/Pico/Pico W/Pico 2/Pico 2W, Loads up to 5A 250V AC or 5A 30V DC

Thoughts:~Overall, nice relay board that works once you figure out its quirks and GPIO pinout.~Setting a pin Low activates the relay, and setting a pin High deactivates the relay.~GPIO pinout:CH1 = GPIO 26 (pin 37)CH2 = GPIO 20 (pin 38)CH3 = GPIO 21 (pin 40)Pros:~Relay board fits good on raspberry pi (I've tested on an rp4).~Decent quality board and relays.~Has GPIO pin passthrough in case your project requires them.Cons:~Included standoffs and fasteners are complete junk~No documentation includedTest script:To test your relays, I've written a simple shell script that will cycle the relays High and Low.#!/bin/bash# written by D Smith# Check if the script is running as rootif [ "$EUID" -ne 0 ]; thenecho "This script must be run with sudo."exit 1fi# Array of GPIO pin numberspins=(26 20 21)# Function to toggle a GPIO pin and print the statetoggle_gpio() {pin="$1"state="$2"raspi-gpio set "$pin" op "$state"echo "GPIO pin $pin set: $( [ "$state" == "dh" ] && echo "High" || echo "Low" )"}# Run loopwhile true; doecho# Set pins HIGHfor pin in "${pins[@]}"; dotoggle_gpio "$pin" dhsleep 0.250donesleep 1echo# Set pins LOWfor pin in "${pins[@]}"; dotoggle_gpio "$pin" dlsleep 0.250donesleep 1done

There's no documentation included at all, just the hat in a static proof bag. It's very tall, but that's to be expected due to the size of the relays, just be aware.Seems to work fine so far, I'll update my review if I do have an issue

Good little kit, highly recommend.