TST control strips monitor time, steam, and temperature for use in sterilization devices (autoclaves). They change from yellow to purple to provide a visual indicator of the success of the sterilization cycle and that all critical parameters of the autoclave (time, steam, and temperature) have been achieved. Use at least one in each cycle; they can be used in individual trays, packages, or bags. Suitable for use with the following cycle: 3.5 minutes at 134°C. Class 6 indicators Box contains 100 units