To calculate the overall star rating and percentage breakdown by star, we do not use a simple average. Instead, our system considers things like how recent a review is and if the reviewer bought the item on Amazon. It also analyses reviews to verify trustworthiness.
I thought that this was a good deal and my doctor told me that I could get the CPAP filters on Amazon. However I noticed that unlike the better quality filters I do not find any dirt on these filters after two weeks of use ( used them for a couple of months now) . The filters provided by the authorized CPAP machine vendors would always turn slightly dark after two weeks . I suspect either the material is not the same or they have not been electrostatically charged. Not sure but I plan to now order these from my CPAP vendor at a slightly higher cost