Marketing InformationThe DuroZone® multi-blade damper for residential zoning systems has been engineered to include many features. Ribbed for strength and extruded from lightweight aluminum, the sleek frame profile provides maximum strength without excessive reduction of free-area inside the ductwork. The extruded aluminum blades are mounted with friction minimizing nylon bushings to provide easy transition between opening and closing. The DuroZone® spring return multi-blade dampers also feature damper blades designed to remain within the damper frame for easy insertion and an external side-mounted linkage for smooth and quiet operation. Multi-blade dampers with a 24 V spring return mid torque motor.