Nispira Activated Carbon Pre Filter Compatible with Holmes AER1 Air Purifier HAPF30AT HEPA Air Filter - 9.5” x 4” x 0.25” (4 Carbon Filters)

I am mainly doing this review because 95% of the other reviews do not even understand what this product is for, or how to even properly install the thing... This product is for any AER1 Holmes filter, or any AER1 Holmes filter replica... If your unit uses the filter it is the correct product... Regardless of what the other reviews say.. This is not a replacement OEM filter for the front cover of the machine, it is a booster filter you apply directly to the FRONT of the AER1 filter. So airflow will 1st go through the OEM filter on the front of the machine, then it will travel through the booster filter, then finally through the Homles AER1... Your Holmes AER1, or replica filter will have longer life with the booster installed. I will include install pictures to further assist everyone...Pic 1 shows filters installed correctly on the FRONT of the AER1, you just line the filter up and gently push it in the sides and top.Pic 2 shows the back of the AER1 with booster installed on the FRONTPic 3 shows the OEM filter installed on front cover, THIS IS NOT THE OEM FRONT FILTER.

The product description is woefully wrong and well for $10 it's not worth going through amazons return system. So I ordered this product for my 242 model air purifier to replace the carbon pre-filter. What the description doesn't say is that this is not a 1 for 1 replacement. This filter only fits over the cartridge and you have to use these dinky little Velcro strips to hold it in place. Where as the original filter, that is nearly twice as long and thick, is held in place with the little plastic spikes built into the air purifier itself. It would be one thing if the filter was a little bit thicker so that i could just use the pressure of the grill pressing on it to hold it in place. But this is just ridiculous. The picture I've provided shows the size difference.

I have an older dog. He pees on the ceramic sometimes. I clean it with vinegar. So: my place smells like vinegar and dog pee. I tried air fresheners and candles. So: then it smells like vanilla... and vinegar and dog pee. I put one of these on the filter unit and in less than hour, it smelled like... nothing at all. It was awesome.I see some complaints on sizing; they fit my unit (Holmes Desktop HAP9243-UA) in front of the HEPA filter. There's an existing black mesh in front of the HEPA filter, but I don't think it's charcoal and left it in place. The replacement doesn't have the hole for the filter check, but I've never found that window reliable. I don't know the longevity of the odor fighting, but it's been great so far.

For people saying these filters don't fit like the old ones....don't realize these are a PRE-FILTERS. These are meant to be fastened in front of then original filters. These are NOT meant to replace the original foam filter that comes with the purifier behind the front cover. These are pre cut carbon sheets. Intended to help eliminate odor in the air. Personally I have not noticed a huge difference in smell around my room that houses the litter box. However they do make the original Aer1 filters last a whole lot longer. Makes the air purifier much quieter without restricting air flow. Very happy with this purchase and will be purchasing again.

**update below 9/2019**These little filters seem to be true to advertising and covered or comprised of charcoal like powder and they are very thin. The thinness is probably good so that when used in conjunction with the tradional filter media, it doesn’t block too much air for the air purifier motor to suck through.The price is in the right spot, and they fit in my unit perfect so I have no complaints.Would I buy again? Not sure. I may just find dollar store “scotchbrite” pads and coat them in my own solution of charcoal or Lysol.UPDATE: after some serious consideration and thinking, I made my own versions of these with the above mentioned ScotchBrite pads and spray 3m adhesive ($5 at most retail outlets) and a little jar of charcoal powder from Wish. They work about the same. I can’t detect any change in my air quality and I am very picky; almost obnoxiously so that I wonder how I can keep a man. Anyway, yeah I wouldn’t buy them again unless they were like 10pack for the sub-$5 range.

Description says this will fit my filter. As you can see on the left, it is too small. They measure 4"x9.5". Original is 5"x11.5". So I will have to try to cut strips from one filter to attach to the edges to see if I can make it fit. Also, the filter is quite thick so I hope it doesn't impede air flow and cause troubles. NOTE: There was another listing that included two of the pleated filters plus 4 of the foam filters. I accidently ordered the wrong one and I regret it.

These are a great pre-filter for your air purifier. The dense structure helps trap any larger particulates, but yet still allows for good airflow into the HEPA filter beneath. The size is just right for placing overtop of the HEPA filter, with no gaps and provides a snug fit for the purifier cover. The downside is that you cannot wash or clean them, but at this pricepoint (and depending on how dirty your air is), you can always get more and enjoy cleaner air!

Arrived on time fit right over the hepa filter and is definitely trapping more dust and is helping with occasional orders, I take the cover off once in a wile and and as seen in the picture it defying traps a lot, as well as it working it also seems to be extending the life of the filter, the filter is a little older then the carbon booster and there’s not nearly as much stuff trapped in it as there was before I added the carbon booster so it seems to be working for me.