Med-Checks pre-printed 9 x 12 sterilization record envelopes are designed for storing Bowie Dick test sheets, recordings and other pertinent data.In addition to indicators for both steam and gas loads, the sterilization record cards have room on the back for information such as sterilization date or type of load. A distinctive color change from blue to black occurs during steam sterilization; and yellow to brown during gas sterilization. Tests for bot steam and EO gas sterilization.