Great product. It mounts on the Pi GPIO header like most HAT's. Supplied with an instruction leaflet that explains how to set it up, download and install the script that controls the fan speed. Once installed you get a desktop icon and clicking on it opens a simple text style terminal window where you type the option you want. You can use default settings or you can enter your own custom fan speed for different temperatures levels. The LED's on the board indicate five speed steps from 10% to 100%. . The fan is fairly quiet when running at 100%. Also the board has a button which allows you to shutdown the Pi in various ways. I didn't test this too much as my Pi case is fully enclosed but it worked with no problems. I expect if the Pi crashed the button script might stop working but in normal circumstances it should work fine. Overall I think this is an excellent way to keep a Raspberry Pi cool.