BT20 / Self-contained Biological Indicator for Steam sterilization processes. Geobacillus stearothermophilus (ATCC 7953) 10^5 or 10^6 spores per vial. Readout: 24 hours. Monitoring vacuum-assisted and gravity air-displacement Steam Sterilization processes at 121-135 °C.After the sterilization process has finished, open the sterilizer door, wait for 5 minutes and remove the biological indicator from the package. CAUTION: Wear safety glasses and gloves when removing the Bionova® BT20 Biological Indicator from the sterilized package. WARNING: Do not crush or handle the biological indicator excessively, since this might cause the glass ampoule to burst.