This Incubator Kit includes 1 Log book, 25 Biological Indicators, Indicator Crusher, 1 thermometer, And the Incubator that can store 14 Biological Indicators. This is a must for those who own an Autoclave. Everything you need to know is in the Easy to use Manual. Step 1: Place Biological Indicator into Autoclave Step 2: Take out Indicator and crush it to release the spores and place it into the Incubator Step 3: After 4 hours, examine the Biological Indicator, to see if it turns Yellow or Purple. (Yellow = Spore Contamination) Step 4: Write down information into log book with date.