The present invention relates to a sterilization process challenge device comprising a solid body comprised of walls which define a space, wherein the space can fully contain a sterilization indicator and a volume of gas of at least 5 cubic centimeters and not more than 1000 cubic centimeters, a container, wherein the solid body is sealed within the container, and a flow restrictor which is attached to or is part of the container, and any gas flow out of and any sterilant flow into the container are restricted by the flow restrictor, wherein the sterilization indicator indicates whether or not it has been contacted by the sterilant for a time and at a temperature sufficient to sterilize an article, wherein the walls of the solid body are impervious to the sterilant, and wherein the walls have a thickness of at least 0.3 centimeter, and wherein a volume of gas of at least 5 cubic centimeters is contained within the container in addition to the volume of gas contained in the space defined by the walls of the solid body.
