It is just the spacer for the HMS Insert to adapt it to the Canyon Cockpit Mount (LINK).
Additionally you need HMS Inserts (LINK) and M3x20 screws, washers and nuts. You could also order a GoPro Mount with a thread, so you'll only need the screws. Change the length of the screw accordingly.
I also added the Fusion360 file, so you could change the height if you want to.
The author marked this model as their own original creation.