This is a vacuum cleaner end with 9mm tip, which can be used for cleaning in various narrow cavities, crevices and holes, such as cleaning a desktop PC inside from dust, for furniture or in a car. There is also a square angled head that attaches to the end of this head. This was made to clean computer heatsinks without removing them and more thoroughly than with compressed air or stock vacuum cleaner nozzles, but it can be used for other things.
It fits a vacuum cleaner pipe with 35mm external diameter.
This nozzle might cause the vac to overheat if used continuously for a very long time due to less than normal airflow, but most vacuum cleaners have overheat protection so don't worry as it'll simply be turned off by it for a while. This hasn't happened to me yet, it's just a word of caution.
0.3mm big part, 0.2mm small part
any, don't use bright colors as dust shows on them
Supports are only needed for the small angle adapter, the main part prints fine without them. Also set them in a way that prevents them from being generated inside as otherwise you will have hard time removing them. Both pieces should be printed vertically.