The Model usually refers to the designation for the living tissue mould around the metal endoskeleton (the skin) of a Terminator (Infiltrator), such as the Cyberdyne Systems Model 101. Early in the design approach, the technological limitations on the minimum size of the endoskeletons restricted Skynet to a much smaller pool of potential Models for use, as they had to be physically large enough to accommodate the Terminator, resulting in the T-800 Terminator and its variant, male and female alike being of herculean or amazonian proportions. Advances in the development of endoskeleton design now allow for a far greater customizable approach to the process, matching infiltration sheaths to the optional chassis construction of units such as the T-888 Terminator.