This a part designed to fit the Nilfisk rubber vacuum nozzle pictured (printed with part number 107401562). The rubber nozzle fits inside this part. It may be compatible with other vacuum nozzles, the port opening is 36mm across with a slight taper inwards.

On its own it's useless, it's shared with the intention that it can be imported and used in other designs to make compatible vacuum or blower ports for tools or other applications.

It is used in my other dust ports for the:
Ryobi random orbit sander:
https://www.thingiverse.com/thing:3893082
Parkside belt sander:
https://www.thingiverse.com/thing:3895715

The stl, step, and fusion 360 files are provided.