Type RS thermocouple wire:  Choose from two different insulation coverings including PVC and Fiberglass.  

Type R/S Wire = (Platinum & Rhodium Alloy / Platinum)

NOTE:  Extension wire is alloyed with copper to reduce cost, and mimic the very expensive Platinum based wires used on the thermocouple without signal loss.

PVC insulation can be used up to 220ºF or 105ºC

Fiberglass insulation can be used up to 752ºF or 400ºC