Model RSD is a round single blade damper constructed from heavy (24) gauge galvanized steel. The 24 volt motor actuator is direct coupled to the drive shaft. It is power closed/spring open (standard). The damper can be field reversed to a power open/spring closed model. The RSD damper may be used with either flexible or rigid ductwork. The RSD has a double layered blade design with an integrated cellular foam gasket to provide a seal when the damper is in the closed position. The RSD also has a Travel Limiter to prevent the damper from closing 100% if your application requires.