Aftermarket Replacement Compare to Hunter Air Purifier Carbon Replacement Pre-Filter for Models 30901, 30903, 30907, 30958, and 30959 Fits all Hunter room air cleaners that require a pre-filter. Cut-to-Fit activated carbon pre-filter helps remove large particles and reduce common household odors. Replacement for 30901, 30903, 30907, 30958, and 30959. Large 16" x 30" cut-to-fit activated carbon sheet! Replace pre filter every 1 to 3 months