Review on Nispira True HEPA Filter Replacement for Envion Therapure TPP440 TPP540 TPP640 TPP640S Air Purifier - Comparable to Part TPP440F, Pack of 2 by Nicholas Peters

Nispira True HEPA Filter Replacement Compatibility with the Envion Therapure TPP440 is a huge disappointment and a waste of time and money. I have the original filter that came with Therapure and after installing it I compared it to this 'spare' and found that the light was shining brightly as there was nothing in it. It cannot be used because there is only an accordion, no internal filter. Unfortunately I waited for the filter light to come on before trying this "replacement" so it's too late to go back. I'd like to think it's a quality control issue, not what it looks like.