I replaced the Filtrete 1085 Air Cleaning Filter just recently (after about our typical 3 months of use). Although I normally don't write reviews to products I purchase and use regularly, clearly I'm making an exception this time. This past month and a half, we experienced a rare late season resurgence of pollen and other allergens which made our overall disposition somewhat less than amiable. The new replacement filter seems to be the reason for greatly improving our general disposition. Now, if 3M/ Filtrete can make replacements last 1 month longer, then I'll only have to use the ladder 3 times a year.