The White-Rodgers Division 7946B1 S23-1 Heating Cooling Sub-Base is a gray plastic unit designed for use with Emerson thermostats. Made in the United States, this square-shaped sub-base is compatible with models 7851B1 and 7851C4. It does not feature programmable thermostat days, but is a reliable and durable component for HVAC and refrigeration systems. Perfect for businesses and industrial facilities requiring efficient temperature control solutions.