Not all filters are created equal. Peak performance is only realized when genuine Vornado Advanced Carbon Filters are used. Usually your carbon filter’s ability to trap odors and gases decreases over time and airflow becomes obstructed as debris builds up. To assure peak performance, it is imperative to change your filter(s) every year with continuous use, depending on your environment, using only genuine Vornado filters. Others may claim to be compatible with Vornado units, but the Vornado Air Purifier is calibrated to achieve a 99.97% capture rate only when used with Vornado Filters. Contains 1 filter. Vornado’s Automatic Filter Refill Program for Vornado Air Purifiers offer a convenient way to receive regular shipments of Vornado filters for your Vornado Air Purifier! Eliminate the hassle of remembering to reorder. Maintain the high efficiency of your Vornado Air Purifier by never running out of new filters. Receive FREE SHIPPING on all air cleaner filter refill orders when you set up a product subscription. Click the “Subscription Wizard” button above to set a customized schedule to receive your filters – conveniently billed automatically. This Advanced Carbon Filter, part number MD1-0027, works with models PCO200, PCO300, PCO375DC, PCO500, and PCO575DC Silverscreen Enhanced Air Purifiers.