A grease filter has a filtering portion configured such that fumes enter a major face thereof and flow through a grease extraction filter therewithin in a direction parallel to the major face. A frame that fits into an opening of a hood defines a box structure that is configured to allow flow from the end (or ends) of the filtering portion where flow exits. The frame permits the flow to exit to a side opposite the face even when the frame is surrounded, edgewise, by a solid structure of the hood opening.