The Rheem-Ruud 42-24195-03K Pressure Switch Drain 40" WC is an OEM pressure switch kit designed to monitor pressure conditions in the condensate drain system of compatible Rheem and Ruud gas furnaces. It operates by sensing pressure changes and opening or closing the electrical circuit when the specified pressure condition is reached, helping prevent unsafe furnace operation. https://www.partshnc.com/rheem-ruud-42-24195-03k-pressure-switch-drain-40-wc