The Honeywell 112630AA Well Assembly with a 3/4-inch connection and 4.25-inch copper insert is designed to house temperature sensors for reliable monitoring in HVAC and hydronic systems. Installed in boilers, chillers, and piping systems, it allows sensors to be easily inserted or replaced without draining the system. https://www.partshnc.com/112630aa-honeywell-34wellassy425-insertcopper