This cable hook is made for creating a cable organisation at the edge of a shelves. The hook has an inner diameter of 30mm and 40mm outer diameter. It fits to an 18mm shelves. You can also fasten it with an M4 screw (or similar imperial sized screw), depending on your needs from above or from below.
This object was made in Tinkercad. https://www.tinkercad.com/things/3pJGniJrYds