pre-filter for Sears Kenmore air cleaners, fits models 83234 and 83353. 3M Filtrete activated carbon pre-filter helps remove large particles and reduce common household odors such as cooking odors, tobacco smoke odors, pet odors, and musty odors. Extends the life of your HEPA and is sold as a four pack. For optimum performance, replace filter every 2 to 3 months.