Both those links are about 1-filter designs though. This is a five filter design which performs better than the sum of its parts. Couldn’t find any sources on that existing earlier, should be added to the article if so

Edit: found an imgur from 2018. https://imgur.com/gallery/hepa-filter-companion-cube-box-fan-jtECP9C

Found a triangle from 2012 https://marshallhansendesign.com/2012/01/02/studio-operations/

Unfortunately both those sources are not sufficient for Wikipedia