The filter covers / pre-filters decrease the amount of dust that hits your filter, reduce dust buildup, increase efficiency of your filters.
QUICK INSTALL: Place filter on top. Press down near the center of the filter with both thumbs until the rubber opening of the filter locks in securely, no tools or hardware needed.
1-layer replacement standard filter is ideal for capturing sawdust and general debris found in the home, garage, or shop. Change filter when vacuum performance decreases, when your vac has a clogged or dirty air filter it can cause it to work harder which will end up hurting your electric bill.