You know how people say "Or not" after someone does the exact opposite of what they say? For instance, you ask someone to pass the salt, and after a few moments of waiting, you realize they aren't going to pass the salt. You would most likely respond with "Did you hear me?" or, "Or not." "Or not" is a pretty common response in situations like this, and I'm sure you've experienced one way or another. You will not be saying "Or not" in reference to the 20x25x5 (19.88x24.88x4.38) MERV 13 Honeywell® Replacement Filter. This filter does everything it claims to do. It captures those unwanted airborne contaminants like dust, pollen, hair, mold spores, viruses, bacteria and much more. The only way you'll be saying "Or not" about this filter would be if you asked it to inefficient, which we're sure you won't do.