A:Answer If your kitchen's pre-installed ducting ends at a 3x10" rectangular opening above or behind, the included damper attachment is the only sheet metal you need. In practice, as an installer you'll want to have duct adapter pieces, some short sheet-metal screws, and high-temperature foil tape handy or close by. Ducting and appliances tend to be "close but not exact" when the installer gets down to mating 'em up.