The CPVC pipe extension is an optional feature that is screwed to the 3" NPT SmartBob II mount. The pipe extension keeps the sensor probe from being pulled up into the standpipe, functions as a bushing, and keeps the cable from fraying on sharp objects if the sensor probe swings while taking a measurement. It also functions to keep the sensor probe flush with the vessel top. The extension pipes are available in CPVC, galvanized pipe, or stainless Steel. They are available in custom lengths from 4 inches to 20 feet. The reason for a longer extension may be to use so the SmartBob II remote can be mounted on a catwalk above the vessel and the sensor probe extended down to the vessel top for easy access to the remote.