Ventilation grille for use in building has rectangular openings in modified U-shaped piece of pressed sheet metal with outward extending flange on one side

摘要

The ventilation grille has a row of large rectangular openings (3-6) in the base of a modified inverted U-shaped (2) piece of pressed sheet metal (1). Thin metal ribs or bridges (14) join the two sides of the U-shape (7,8) together. There is an outward extending flange (13) on one side. Several U-shaped pieces of metal may be joined together end-to-end.