OK Steam Sterilization 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 time exposure. 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 indicator dot printed on the distal end of the 8" strip permits a secure sterile presentation. Only if this dot is dark may sterile personnel handle the strip and the package contents. Without such assurance, contamination of personnel becomes a real risk. For steam sterilization cycles of 250°F (121°C) and 272°F (134°C). Measures 0.56"W x 4"L. Sold 250 per box.