The HART & COOLEY Round Butterfly Damper is an all-steel construction damper designed to control air volume evenly across a #16 diffuser. Featuring a removable knob operator, this damper allows for smooth adjustment from closed to fully open, ensuring precise airflow control. The knob also holds the diffuser in position while attaching face screws, making installation and adjustments effortless. Ideal for HVAC systems, this durable damper offers efficient air management for both residential and commercial applications.