The Honeywell MS4120K1000 Ruskin Actuator RLH-120 is a reliable HVAC damper actuator designed to provide precise control of air dampers in ventilation and air-handling systems. It works by converting an electrical control signal into mechanical movement, allowing the connected damper to open, close, or adjust airflow as required. Commonly used with HVAC air handlers, ventilation syste... https://www.partshnc.com/honeywell-ms4120k1000-ruskin-actuator-rlh-120