Indicator strips used to ensure that the correct sterilisation conditions have reached packaged instruments. Monitors one or more sterilisation processes for the purpose of detecting sterilisation failures in packaging, loading or steriliser function. Steam, rather than heat alone, is required to initiate colour change. Provides permanent record of compliance. Indicator turns from blue to black when exposed to sterilisation. 3.5 minutes at 134°C, 1.5 minutes at 121°C.