The Honeywell M436A1116 Spring Return Normally Closed Damper Actuator with auxiliary switch is designed for reliable control of air dampers in HVAC systems. It operates by driving the damper open when powered and automatically returning it to the closed position upon power loss, ensuring safety and airflow control. Commonly used in air handling units, ventilation systems, and zone control applications, it improves system efficiency and reliability. The integrated auxiliary switch enables precise status feedback, supporting enhanced control, energy savings, and consistent indoor air management.