I just bought these filters for my Shark Rotator Lift Away True Pet. We have a black lab at home; So I have a habit of washing the foam barrel filter weekly (pet hair is pretty nasty!). The double pack is PERFECT because I always have a backup filter with me when I wet-dry. I probably waited too long to replace my HEPA filter - I think I just forgot it was there! It's probably better to switch a few times a year. The last set of filters I ordered lasted about a year so I'm very happy to be buying the same set again. I agree with the other reviewer that the small flat disc felt filter that sits under the foam cylinder filter appears to be a bit thinner than the stock filter; but I don't have to wash them that often and they seem to be holding up great.