Product review (2 stars): Pointless. Makes no difference in a non-ducted hood.
Used with a crappy H-D NuTone hood which came with our house. The previous owner installed the hood without venting it because he was an idiot and a foe of all things that are good and right in the world. This meant that my wife would consistently set off the smoke detectors when she seared anything on the stove top, because the useless hood just recirculated the smoke. We ultimately replaced the hood and vented it properly, but before we did, as a stopgap, we tried these to reduce smoke and smell in the house. There was no notable change at all. We couldn't tell any difference between using the stock filters and these carbon filters. If your hood isn't ducted, they won't help. Do yourself a favor and install a ducted hood. These filters are a half measure that accomplish nothing as far as we could tell.