This is a T-type thermocouple wire with blue braided fiberglass insulation, which is good up to about 400 C Celsius or 752 F Fahrenheit. This T-type thermocouple wire can be used to make your own T-type thermocouple for a wide range of applications, or to make your own extension wire. T-type thermocouples are frequently used to measure cold and ultra cold temperatures in cryogenic application. This T-type thermocoule wire can measure the temperature of liquid nitrogen, dry ice and other cooling fluids used in cryogenics. The copper constantan wire is made to standard T-type thermocouple specifications. Type T thermocoules can measure from -418 F to + 752 Fahrenheit ( or -250 degree Celsius to +400 degree Celsius) They are the best thermocouples for extremely low themperatures and cryogenics. This t-type thermocouple wire is sold in a precut 10 yard (30 ft) spool. If you need a longer Type T thermocouple wire please look for a different listing.