Single pack Dreamstation 2 Filter CPAP filters are an essential CPAP supply used in everyday sleep maintenance. This reusable filter is used to remove dust, pollen, and smoke particles before they reach your airway through your CPAP mask. Over time, these filters can become filled with dirt and bacteria that can become harmful if ingested. It is recommended to clean this pollen filter every 2 weeks or when needed depending on appearance. Replacement typically occurs every 6 months unless you notice a considerable amount of dirt when cleaning regularly. For best results and to extend the life of your CPAP machine, following a strict cleaning and replacement schedule promotes healthy sleep therapy and saves you money! Please Note – the gray backing is not meant to be removed as it holds the filter together to provide efficient filtration.