If you have a Port Package, you have these air filters in at least two spots in your house and should learn how they work. You should change the filters every six months. They’re prox. $5.
They aren’t any super-special material–they’re mainly for filtering out big things, but they do help. And they do break down over time.
Note: This product is often out of stock. If it’s unavailable from Therma-Stor, you can go here to get a similar product: https://www.positive-energy.com/product/fresh-100-replacement-filters/. Please note that this will need to be trimmed to fit.