Rating is not based on scientific analysis but based on observation and long-term use. The 1600 MPR appears to substantially reduce as claimed pollen, pet dander, smoke, bacteria and viruses. The latter two elements cannot really be determined. Changed every 2-3 months and the amount of collected debris in the filter is supported of filtering.

This is a really great deal for filters that need to be changed every 30 days. It gets so expensive when you have to buy them one at a time so I was really happy to find a four pack! They have all sorts of sizes and honestly, you can buy three of them and get by for a whole year!

I know HVAC workers will cringe when I say this, but we really like these better than the cheap ones they HVAC workers say to use. I don't think they're a waste of money. Having the pets we have, being smokers, and living in an older house that's hard to keep dust and dirt out these help much better than the cheap ones. Instead of changing the cheap ones 1 or 2 times a week, we can sometimes go almost a month with these

Great brand, great filter, great price.

I was so glad to see that Sam's had the size filter I need.

Very good filter. Very good orice!

Good price on good filter.

These work great for our system.

I am happy because my daughter have allergies with this filter it works to recive fresh air.

Very good filters for allergens at a great price