Product review (4 stars): Provide Much Needed Additional Filtration for Non-ducted range hoods!
The stock filters really can't do the job by themselves.  These charcoal filters clip on to the factory filters and provide the much needed filtration.  Still if you have the option to provide ducting for your range hood you will be much happier.  If you have to to keep your range hood non-ducted, you'll be pleased with these.  There is a strip on the filter that tells you when they need to be changed.  We haven't had them long enough to see how these strips work but they sound like a great idea.