The BI25 is a self contained biological indicator for monitoring steam sterilization processes. It contains a 10^5 population of Bacillus Stearothermophilus spores and the nutrient. The indicator conforms to ISO 11138 parts 1 and 3. BI25 belongs to the Clinichem BioTest concept of biological indicators including also an incubator and crusher. 25 indicators/pack.