The PCD Test sets include process challenge devices (PMS) with different air removal characteristics. The test sets have been developed to monitor the penetration characteristics of the sterilization agent to ensure penetration inside of the hollow devices, e.g. minimal invasive surgical (MIS) instruments and tubes. Air and non condensable gases (NCG) must be removed from the inside of hollow devices before they can be sterilized. Hollow devices and MIS instruments are more difficult to penetrate and therefore to sterilize than porous loads.