Product review (3 stars): 3 weeks?
These work awesome but after 3 weeks they're turning brown and shedding and have several dry hard spots on them. It seems they've reached their life expectancy but you'd think they'd be made of a more dureable material. Even with them as ugly as they are, they still function though.

I flip these filters every night so that the outside area becomes the inside in hopes of making them last longer.