Holmes Air Purifier 14ALL Carbon Pre Filter (Aftermarket) Fits Holmes models HAP-290&#44; 475&#44; HAP-300&#44; 3004&#44; HAP-291&#44; 2914&#44; HAP-292&#44; HAP-70&#44; Large 15-3&#47;4 x 48 cut-to-fit activated carbon sheet. Helps remove large particles and reduce common household odors such as cooking odors&#44; tobacco smoke Makes 1 to 6 pre-filters depending on the model. Saves money. For optimum performance&#44; replace pre-filter every 2 to 3 months.