That's typical for NH, not sure about the others. Make sure you keep the old one you removed and clean it out. I suggest you wait until it's noticeably dirty to swap then, then take the old one out and wash, not blow it clean. Usually I do this by filling a large tub or bucket with very warm, but not hot, water, and lots and lots (about a 1/2 to a full cup) of liquid detergent, and let it soak for about 1/2 hour. (fill the bucket/tub first and then stir in the detergent - otherwise you'll end up with a ton of suds and little or no water.) After, soaking wash the filter by lifting it in and out of the water so that the water is flowing as much as possible from inside the filter to out. Once clean rinse it thouroughly including at least once putting it in a tub of clean water to finish the process. Hang it to dry. Make sure it's hung somewhere were drying will occur within the day. I've washed my old Ford 1720 filters numerous times like this. Just make sure to be gentle throughout the process so as not to damage the filter. Whatever you do, do not use anything like compressed air on the filter while wet.
