This is adapter for HEPA filter behind ventilation.
Its designed for HEPA VACUUM SENCOR Filter.
You can buy filter on this : https://www.amazon.de/-/en/SVX-013HF/dp/B00KXWLBL2 . I buy there: https://www.alza.sk/sencor-svx-013hf-d4525432.htm . Its really fit.
The model has holes for 6x3 neodymium magnets. Which you stick in the holes with glue.
I recommend printing at least PETG or ASA.
When printing different materials, especially ASA, there is a big difference in air quality for me.
Thank you for your feedback.