IREALIST Filters-Now RLHAPF220 HAPF220 Holmes Air Purifier Carbon Pre Filter Fits Holmes model HAP222&#44; HAP223&#44; and HAP2234. Measures approximately 4 1/2 x 8. Helps remove large particles and reduce common household odors such as cooking odors&#44; tobacco smoke 2 carbon pre-filters per box. For optimum performance&#44; replace pre-filter every 2 to 3 months.