The Resideo 40003918-006 2-Way Conversion Kit is a high-performance water control accessory designed to convert 3-way zone valves into 2-way operation in hydronic HVAC systems. It enables precise water flow regulation for boilers, radiators, and heating zones, improving system efficiency and responsiveness. https://www.partshnc.com/40003918-006-resideo-2way-conversion-kit-water