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. MADE IN THE USA 45mm THERMOWELL ASSY FOR L/P 6L VESSEL, SEAM WELDED - ELECTROPOLISH FINISH, 316L SST MATERIAL, SUPPLY WITH S/CAP (A523-599) & WHITE SILICONE LINER (A523-600), 1- THERMOWELL TUBE: 5/16"OD X .242"ID X 1.0" above x10 9/32" insertion, 1- SIPHON TUBE: 1/4"OD X 5/32" ID X 1.0" above x 10 9/32" insertion, 1- VENT TUBE: 1/4"OD X 5/32" ID X 1.0".