This was actually a 20 25 1. I am very pleased, in the morning I always wake up with a semi stopped up nose. The first morning like clock work, use the restroom, blow my stuffed up nose. I couldn't believe it, my nose wasn't stopped up. My dog has breathing problems, when the air cuts on at times she has problems breathing, no more it has been such a relief. I didn't realize how drastic an improvement it would be, thank you.
Love these filters, especially through the high allergy season in our region from November to April. Great fit, easy to change and one order lasts all year.