Review on GPIO Expansion Board for Raspberry Pi 4B/3B+ with Screws - HiLetgo Raspberry Pi Shield by David Turner

This product offers you good terminal blocks as a quick connection option for some projects. The problem is the lack of documentation explaining how this is done. I was playing around with the continuity setting on my voltmeter and found that the terminal blocks have no connections to the main GPIO header. Then I noticed that the numbers and letters along the terminal blocks seem to match the numbers and letters on the internal connectors. And then a lightbulb went on in my head! That's what this sweater bag was for! You need to connect the terminal blocks to the internal pin headers that have traces to the GPIO header on your Rasp Pi on the adjacent row of pins. It is customizable to your needs. HAVE FUN!