The HEPA Wunderbag is designed to give superior filtration to nearly any wet-dry vacuum on the market. 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 to halt particles down to 0.3 microns to ensure that no dust escapes back into the air. It does not have to be removed when vacuuming up water and slurry as it will retain its strength and filtration, even when wet. Each size of HEPA Wunderbag can withstand the approximate weight of whatever your barrel can hold! When you are finished with the bag, simply seal it, and throw it away, leaving your vacuum clean and uncontaminated. Includes (2) HEPA Wunderbag Pre-Filter Bags. NOTE: The HEPA Wunderbag DOES NOT make your vacuum HEPA certified by any regulatory standards.