Used this to capture drywall dust on different fans during a remodel.Also put one in my HVAC for a few weeks after the remodel was done to capture any lingering dust. There is definitely a higher pressure drop with this than other lower MERV filters, but it did not affect my system enough to make a difference.You get a $54 filter for 1/4th of the price. Same filter without the colorful packaging.The product is in place in my home and working just fine.I've converted to purchasing these over the over-priced Honeywell filters I can get from the local big box store. I'm able to get a higher MERV # for less price, more in a pack, and a better end result in the air quality of my home. Very satisfied with these and will stick with Aerostar for the foreseeable future.Love the fit and function.good filtersExactly as describedThe filter put in my air conditioner fell apart in a week, the filter stuck and got soaking wet. The edges aren't glued down properly so the felt us loose. I would never purchase this brand again.They 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.