The finest filter of the K40 DIY air filter build.
In the US the equivalent filter classes are MERV 15 and 16.
Cost of this article are around: 20 EUR
You can purchase the article under the following links:
- Amazon.com (International)
- Amazon.de (Germany)
- Pocket filter we used for the K40 DIY air filter in a German online shop
Disclosure: Some of the links above could be affiliate links. This means that - at no additional costs to you - I earn a small commission when you purchase products through these links.