Backer Marathon's mineral insulated thermocouples are a fast acting and rugged alternative to general purpose thermocouples. Mineral Insulated Thermocouples also are better suited for high temperature requirements. Since the calibration wire is encased within a metal sheath packed with magnesium oxide the thermocouples can withstand higher temperatures and depending on the application will last longer since they are more durable. Another feature of Mineral Insulated Thermocouples is faster response time. We offer quick turnaround, usually 48 hours or less, on custom designed and manufactured units.