They're hard to find, but worth finding. They keep my air and air conditioning coils nice and clean. I have 2 Labs that drop chains - a lot. These filters prevent everything, their dander and everyday dust from circulating through the HVAC system. I change mine monthly. Sure, they're not cheap, but they're certainly cheaper than allergy medication and HVAC service calls or replacements. They even help keep dust on surfaces indoors. Can't find them at Home Depot anymore, but this seller sells a multipack that saves money despite shipping. On the plus side, all packaging and shipping materials are recyclable. I recommend them with enthusiasm.
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