Used for monitoring steam sterilization (250°F gravity; 270°F gravity flash; 270°F prevacuum) or ethylene oxide sterilization processes. Each indicator vial contains a disc inoculated with spores of Bacillus stearothermophilus and Bacillus subtilis var. niger, positioned for improved exposure to sterilizing conditions by a unique plastic holder. The vial also contains an ampule containing a specially formulated and optimized soybean casein digest growth medium combined with a pH indicator. The vial label is printed with chemical process exposure indicators for steam (250-270°F) and ethylene oxide. Requires incubator, # 35-2486. Due to the nature of this product, shorter expiration (use-by date) dates have been assigned to ensure product integrity.