10 labels per pack. How the temperature labels work. The indicators white thermo-graphic ink area (square) is manufactured and calibrated to a specific temperature level that turns irreversible (permanent) black when its rated temperature is exceeded. Accuracy 1%. Changes occur in less than one second. The thermo-graphic ink area is hermetically sealed against moisture, oil, grease, fuels, solvents, water and steam. To Apply: Pull the flexible, self-adhesive label from backing paper. Place on cleaned surface for maximum contact and adhesion. That surface temperature is now monitored for hours, days, months or even years, as long as the indicator is attached. Our Labels are the most economical, dependable and easily applied temperature recording method. No equipment. No special skills. Apply and forget until you inspect.