Thermowell assemblies are used to hold inside one tube the rtd temperature sensor that monitors the temperature within the vessel in conjunction with a temperature controller. There are also tubes for addition of media and vent tube Thermowell assemblies for 1965 and 1967-style angled sidearm flasks, 3-port 5/16" od Thermowell tube,1/4" siphon and vent tubes Includes 45mm pp cap and silicone gasket Seam welded and electropolished 316 l stainless steel 32 ra finish or better Longest tube length: 10 1/2"