What is used on the filter to help it retain dust? Hopefully not some sort of oil like they use on the engine air filters? They don't say much about what is used to treat the filter after washing it.
Cabin Air Filters | Washable, Reusable and Replacement Filters | K&N
Buy washable & reusable cabin air filters from the official K&N site. Help protect against dust, allergens, and more by replacing your cab filter.