Breathe Naturally brand Carbon Pre-Filters for Honeywell HPA300 series air purifiers. Filter Measures: 14" x 17.2" x 0.2". Compatible with: Honeywell HPA300, HRF-A300, Pre-filter A & HRF-AP1 series air purifiers. This listing comes with (4) Carbon Filters. Breathe Naturally’s carbon pre-filters are not only thicker than leading original equipment manufacturer (OEM) brands, but also cost less. Trap foul odors, dust, dander, pet hair and other airborne particles. 100% Satisfaction Guarantee – We guarantee you will love our carbon pre-filters or your money back. No questions asked. Breathe Easy knowing Breathe Naturally has your back. We recommend changing your carbon pre-filters every 1-2 months based on use. Carbon pre-filter material made in the USA. Cut, packaged and shipped from Minnesota.