Ive been buying Filter Buy filters for 3 years, since we moved here, because those were the filters in use when we got here. Ive reordered the MERV 8 but this time (2 weeks ago) decided to upgrade to MERV 11. So far so good. The filters get dirty after 3 or 4 months so they are working. And our HVAC system seems to be happy. Also the price is very good. This latest order is the first where I did comparison shopping and I chose to reorder from Filter Buy.