The Verify Self-Contained Biological Indicator System is designed to monitor steam and/or ethylene oxide (EO) sterilization processes. Each Verify Indicator consists of a plastic cap and vial containing a disc carrying Geobacillus stearothermophilus and Bacillus atrophaeus spores and an ampule of bacterial culture medium combined with a pH indicator. In addition, these biological indicators are available in single species E6 populations. A color change from blue to yellow after activation and incubation gives unmistakable evidence of microbial growth. The chemical process indicator printed on each Verify vial label shows that minimal process parameters were attained. Each lot of Verify Biological Indicators is produced under tightly controlled conditions and thoroughly tested to ensure compliance with STERIS's strict quality requirements.