Shopsmith heavy-duty, Filter Hoods are made especially for our Dust Collector and cleans the air that's returned to the environment once the dust is removed. As it does this, a cake of dust forms on the inside of the Hood. As the build-up thickens, the Hood traps smaller and smaller particles, increasing its dust-capturing efficiency. The 24 Inch Filter Hood is twice the size of the OEM 12 Inch filter hood and can capture particles as small as 5 microns. Made of a special polyester felt, our Filter Hoods are fully washable.