Product review (5 stars): So happy to find this -- big box stores no longer have them
Just bought 2 condos and they have 2 older fans from when the condos were built in 1974.  The fans are fine, but these round filters are impossible to locate in the stores.

Easy to replace and so nice and bright.  I usually put mine in the dishwasher monthly for cleaning.

They do exactly what they're supposed to do -- filter the grease from cooking.  I couldn't get rid of a bad fish odor in one of the units until I replaced the filter.