A piece of stock scenery hardware, most often used when flying flat-framed scenery. Usually come in pairs. Top Hanger Iron: Affixed to the top of a scenery flat for hanging. Bottom Hanger Iron: Fits under the bottom member of a scenery flat. Usually secured parallel to the Top Hanging Iron. Pictures from http://www.mutualhardware.com/Theatrical-Set-Hardware/Hanging-Hardware . Not to be confused with Hanging iron, used for mounting striplights.