These filters are exact duplicates of what was supplied with the Aprilaire Model 1750a unit when the unit was brand new. Having these spares filters makes change out a matter of a minute instead of 30 - 60 minutes. Prior to owning them, the procedure was to shutdown, open the filter access panel, remove the filter, clean the filter, (20+ minutes if setup to do so) dry the filter (30+ minutes minimum) reinstall, close it up and restart. I was looking at a minimum of an hour and it had to be done immediately. Now, I shutdown the unit, open the access panel, remove the dirty filter, install the clean filter, close the panel and start the unit up. Less than one minute of down time and I have the option of cleaning the old filter at my leisure and allowing it to completely air dry without forcing the drying time.The fit was perfect for my AprilaireThis is not the quality of the original filter that came with the Apriaire. There is only a metal mesh support for the filter on one side of the spongy filter material. This makes the frame for the filter less sturdy. Packaging for shipping was also shoddy; the box arrived half open with the filter's frame slightly bent. It was all less than I'd expected.Arrived ahead of schedule.Item was manufacturer labeled and delivered in excellent condition - contrary to other reviews.It is installed and working perfectly.I have a model 1750A dehumidifier.The filter did not have packaging to protect it. As a result, it arrived damaged. We were able to make it useable and did not have time to get it replaced before installing. It does appear to be working.This was just fine as is. I only wish Aprilaire had one with a higher MERV rating so that it would catch more incoming allergens.This is a simple installation, and fit perfectly. And amazon wants 12 more words, but there is no more to say.