Thanks for your reply. I've elaborated some in the grandparent. I am willing to pay for quality once it is rigorously demonstrated.

The safety issue comes down to this paragraph in your FAQ:

What is the filter material and how is it tested? Our filters are made in the USA with material tested to >99.997% VFE (viral filtration efficiency) by Nelson Labs. Another metric is PFE (particle filtration efficiency). The N95 standard for 0.3-micron PFE is >95.00%, while Narwall's filter material is tested to >99.50% 0.1-micron PFE. You can learn more about these particle sizes here.

The way I read it, you test for 3um (VFE is that according to https://fixthemask.medium.com/the-standards-for-face-masks-i...) and 0.1um, but not 0.3um. I'd be happy if you could point me to papers that those two sizes cover 0.3um and saturation issues.

Is there some kind of independent verification of efficacy and safety of the whole device, not just the mask?

As a minor point - the sticker price is closer to $820 (4 persons times mask and 6 months of filters and international shipping).

I am legally required to wear a medical-grade mask (FFP2 or surgical). Do you have an official-looking document to show to the authorities?