Hood filters are installed over stoves and are designed to capture and remove smoke, grease, and debris to prevent them from getting into the ventilation system. Without these hood filters, grease, particulate matter in smoke and other types of debris would build up in the air ducts and could become a fire hazard. Range hood filters are very important for homes and commercial kitchens. http://www.dm-gfilter.com/baffle-grease-filter/range-hood-filter/