Bowie-Dick Test Pack is designed to check effective removal of air from the sterilizer chamber after vacuums are drawn for pre-vacuum steam sterilizers. This article may be directly applied without the need of preparing standard pack by staff. After one sterilization cycle, take the paper out and observe the color changes of its yellow bar pattern; uniform black indicates normal steam penetration and thorough removal of cool air (<5%) from pre-vacuum steam sterilizers or high vacuum autoclave with pulsing systems; non-uniform color changes or no changes of local color means incomplete removal of cool air from pre-vacuum steam sterilizers or high vacuum autoclave with pulsing systems, presence of cool air in articles pack or abnormal stream penetration.