The Honeywell C7660A1000 Dry Bulb Temperature Sensor is a duct-mounted sensing device designed to measure return air temperature in HVAC systems. It operates by detecting air temperature within the duct and transmitting a proportional 4–20 mA signal to the system controller, enabling accurate heating or cooling adjustments. Commonly used in air handlers, rooftop units, and economizer control systems, it supports precise environmental monitoring. Benefits include improved temperature regulation, enhanced energy efficiency, reliable system control, reduced operational costs, and consistent indoor comfort in commercial and residential HVAC applications.