The Wunderbag is designed to be used with most wet dry vacuums. As a pre-filter, it is installed in the barrel of the vacuum and filters dust, debris, and other contaminants before they reach your filters, extending your filter life up to ten times as long. The five layers of filtration within this bag are rated at .5 microns of filtration to ensure that no dust escapes back into the air. It does not have to be removed when vacuuming up water and slurry; it will retain its strength and filtration. One Wunderbag can hold up to 40 lbs of dust and debris. When you are finished with the bag, simply seal it, and throw it away, leaving your vacuum clean and uncontaminated. Includes (2) Wunderbag Pre-Filter Bags.