The Johnson Controls M9220-600 Jackshaft Coupler is a mechanical linkage component designed to connect actuators to damper shafts in HVAC systems. It works by securely transmitting rotational motion from the actuator to the jackshaft, enabling precise control of airflow. Commonly used in air handlers, ventilation units, and building automation systems, it ensures reliable damper operation. Its use enhances control accuracy, improves system efficiency, and reduces mechanical wear, making it an essential component for consistent and effective HVAC airflow management.