Gas-Chex Sterilization Indicator Strips have the easiest-to-remember color scheme: Red for Stop (pack was not yet processed or the process was inadequate), and Green for Go. Gas-Chex Strips are suitable for monitoring gas concentration and exposure, and are especially suitable for ascertaining adequate humidification during the cycle. In the absence of humidity the color change to green will not occur, even if the other exposure conditions were adequate. 8" Gas-Chex indicator strip features a special diamond-shape indicator that aids in sterile presentation. The "Gas-Chex" end of the strip should be placed in the portion of the package judged to be the most difficult for EO gas to penetrate.