Pictures say more than 1000 words. It´s a Desk Cable Organizer Port for Holes in your Desk. :-)
So what else can i say…

It fits 2 7mm cables and one up to 5mm if you want to use the cap else it fits more.

It´s for Holes with an diameter of about 58,5mm (measured)
I`ll add some more later. I need a second one for 62,5mm but it´s still work in progress.

Part 3 is a cap to hold the cables in place. you don't necessarily need it. I dont have a picture of it atm, only a cad screenshot.

happy printing