Dayton square motorised fire / smoke dampers are suitable to control emergency fire or smoke in commercial buildings. These combination dampers feature a fusible link that allows the solder alloy to melt when the temperature crosses over 165 degrees F and automatically shuts off the access to HVAC fans & ductwork. They are made of 16 gauge galvanised steel to withstand high temperatures and can be mounted in both vertical and horizontal positions. Choose from an extensive range of these combination dampers, available in 7.75 to 23.75 inch heights.