I have ordered these for my neighbor since does not have a car to drive and these work very good so every 6 months he ordered new one as the ac and heating say to change them every monthThanks PeteAs an allergy suffer who needs to adult and not be stuck in bed because I can't breathe and or have a sinus infection migraine, I'm grateful that these work and they're cost-effective so I can change my filter as regularly as I should to keep my sinuses healthy. I'm on my second pack.These are hard to find in a store (I wasn't able to find any), due to the unusual size. I found them on Amazon and the price for the MERV 13 was better than some of the other brands lower rated ones. These fit just like they should in my space. I am remodeling an older house with these size filter.The value was great for this level filter; it fit fine; it has made a noticeable difference in the obvious dust in the air. I will be buying more.Excellent price for 6 filters. 2 of the 6 filters, one corner coming undone/unglued.Good solid filters, seems to be working as designed, it’s a great product. It’s a little higher priced.Outstanding price and very efficient service and shipping.Worst filter I have ever bought. I would give it a zeroGreat price for a MERV13 FilterThey are better than the Merv 11- they have a couple more pleats - making them have more material and folds. The only problem is that unlike the real expensive 3M -don't last quite as long. I get a month out of one- but only got a month and a half out of a 3M as I have severe allergies and they hardly look the slightest bit dirty when I change them out. They are so much more affordable. As of these size issues- I don't see much of an issue- tiny difference. I use a pinter's tape on the edge - taping it to the frame and always have with other filters to keep it in place.Como tal, cumple especificaciones. Se confía en la calidad. De observación, si es del interés para armar un cubo de Corsi-Rosenthal (popular como alternativa de purificador de aire, en tiempos de pandemia), sugeriría los de 2 pulgadas de grosor. Desde luego, los de 4" son más aparatosos, pero creo que estarían sobrados para uso doméstico.You should use a MINIMUM MERV 8 in your furnace for better living. I changed out my furnace filter and in 2 weeks it's already black. There's a lot of stuff in the air you breathe in your house.I was also looking for replacement filters for my Sharp FPP40CX, so I bought the MERV 13 for my FPP40CX, I cut them in half for a perfect fit with foam tape on one edge for a perfect seal.Add a foam prefilter for air conditioners on top to catch more dust and longer lasting filters before changing.I hope that helps for people looking for replacement filters for their Sharp FPP40CX or other sharp units.I have been buying filters for long time for various properties.This is unpresentable, unprofessional.How bad does it get?They asked me to remove negative review for full refund otherwise charging restocking fee $26.Plus shipping $38, cost me ~50% to return low quality product.AVOID!!!I don't believe these ones are true MERV 13 - I counted the pleats compared to the one I removed -and sure enough less pleats, therefore less filtrations, less material. Some of the wire was cut. One filter had bends in the pleats. I had this brand before- was it the supplier trying to pass off less than perfect ones? They were pretty good about returning them and refunding.