OK Strips are indicators that monitor all critical sterilization parameters: steam, time, and temperature. In sterilization cycles OK Strips guard against incomplete steam penetration, presence of non-condensing gases or excessive air, as well as from inadequate temperature or insufficient exposure time. The pre-printed standard reference color permits rapid and certain visualization of the results. If the sterilization conditions meet requirements, the arrow and the K will change to become at least as dark as the reference color O forming the OK expression. The color response pattern may be used for sterilizer diagnostic evaluation.