Error-free, in-office read-out biological (BI) system certified for use with saturated-steam-sterilization processes including liquids. Doesn't have to be transferred to culture media or activated by crushing prior to incubation at 56°C. Simply process, incubate, and record results. Purple-to-yellow color change after incubation indicates spore growth (non-sterile) or sterilizer failure. Can be used with the Proof Steam incubator. System does not include sterilizer.