Bilco automatic smoke vent dsh-4848, double leaf, galvanized steel, 48″l x 48″w aid firefighters in bringing a fire under control by removing smoke, heat and gasses from a burning building. Type dsh double leaf smoke vents are the most economical way to add fire venting protect in large areas such as warehouses or manufacturing facilities. Vents are available in steel or aluminum construction and in a number of standard ul-listed sizes exhausts noxious fumes and gases in the event of a fire fusible link activated.