This HEPA filter is for use with Seaira Watchdog 550 dehumidifiers. It sits behind the pre-filter on your Watchdog Crawl Space Dehumidifier. It is used as a replacement filter for the standard MERV-8 filter that is included with your dehumidifier. A HEPA filter is extremely effective at removing the smallest dirt and dust particles from the air. It is recommended that the filter be changed about once a year. It is not washable.
The W-518 comes in a 3 pack. Actual product may differ from photo. The Watchdog 550 filters are more rectangular.