General Purpose Type Thermocouples and RTDs have a plain sheath with no permanently attached fittings. They are usually mounted with the use of a compression fitting which is supplied separately. Tip temperatures can be as high as 480°C (900°F) for fiberglass insulated wire, 250°C (500°F) for FEP insulated wire. Models specified with a head cover include a 1/2" hex nipple. For higher temperatures, see "Mineral Insulated Probes".