Whirlpool 8171434K (8171434), 4-Pack (Large), Air Purifier Active Carbon Pre-Filters, Fits Air Purifier Model AP51030K, AP45030K, APR45130L, WP500, 18x16.5 inch

I purchased the Whirlpool 8171434K Large Air Purifier Carbon Pre-Filters to replace those in two Whispure AP51030K units that I am running. I only purchase items directly from Amazon, so I can't speak to the other reviews complaining about 3rd party replacement filters being shipped instead of the OEM filters--the filters Amazon shipped to me are genuine Whirlpool filters.The pre-filters have small slits pre-cut towards the top of the filter, which makes it very easy to position the new filter exactly where it needs to be on the grill. Once placed onto the front grill's guide tabs, all that's required is gently pushing the filter material into place and reattaching the grill to the air purifier.I have been very impressed by the amount of dust and pet hair that these pre-filters are able to capture within their 3 month lifespan. The primary purpose of these filters is to capture the larger dust particles, thereby extending the life of the more expensive HEPA filter (which gets changed once per year). Despite the relatively small amount of activated carbon in these pre-filters, I have been impressed by their ability to quickly neutralize light cooking and catbox odors.In my opinion, these filters are a great value and perform as expected.

Works well. Easy to install.

Brief background: I am a physician living in a very polluted city, study the effects of industrial and traffic related air pollution since 1995, test different air purifiers, filters and air quality monitors, have PURCHASED most of my equipment from Amazon and publish some webpages about air pollution. I am very sensitive to air pollution and usually detect spikes several minutes before good sensors detect them.The carbon filters are thicker than original. They do the work as carbon pre-filter which means they get easily clogged so you must vacuum them quite often depending on use to fully protect the HEPA filter. I would say once a week but it depends on how dirty the filter is.The filters are ok. The problem is the air purifier design.TIP for the carbon filter: you can wash them and put them on the sun for 1 hour so you can reuse them. I have tried it just one time and worked. The sun light has UV light that ionize polulants removing them from the filter. I recommend washing the carbon filter first then put them on the sun.

This stock replacement fit as expected. I didn't notice any difference in odor in the room as the room doesn't have any odor to begin with. However it does work well as a pre-filter to the main filter and perhaps prolonging the life of the main filter because the larger amount of dust can be vacuumed from this filter before it reaches the main Hepa filter. In the end, it probably saves money from having to purchase the larger filter so often.

My kids have asthma and dust allergies and we've been using these in their Whirlpool purifier for years. The amount of dust that the prefilter traps is both satisfying and alarming, but great to know that it helps clean the air in their rooms!

Perfect replacement.

Fits well in the machine, and works as expected.

This keeps the main filter clean. I vacuum the pre-filter once/week. They last a long time. And the main filter lasts for even longer.