Winflo carbon filters / charcoal filters with 2pcs set are designed for select non-ducted/ventless range hood installation. Only fits select Winflo range hoods. Filter size is round 7.5" x 7.5" X 1.5" See manufacturer sticker inside bottom of range hood to ensure correct filter part size. They are attached to the range hood blower to clean the air before recirculating back into the house. Duct work is not necessary. Winflo carbon filters are the solution for the kitchens that don't have an exhausting duct option. This carbon filter fits some Winflo under cabinet range hoods and some wall mount and island range hoods.