Product review (4 stars): Cannot tell if its even effective to replace the filter.
I didn't realize the Greasy filters needed to be replaced periodically. After replacing the filters, he suction of the Range Hood is still not satisfactory and I can't tell if its due to the filter or not. After replacing it, I have not noticed any difference in Range Hood Performance either. I just visited a previously "new home" that's about 9 years old and the owner apparently never once replaced the Hood filter - and it still works - so i can't even tell if its worth it to replace the filter...
I'll give the product a 4 star, but due to the lack of perceived difference I can only trust that it will prolong the life of the Range Fan...