PTFE adapter for use with either 1/8"; or 1/4"; thermocouples. Adapter has an outer Viton® o-ring to form a grease-free, airtight seal between the adapter and the listed size of outer joint. The compression nut works in conjunction with the upper Viton® to provide a airtight seal between the adapter and thermocouple. Adapter design permits use with CG-145 Keck clips.