Expanded metal is a sheet metal mesh. It is made by stretching a slitted sheet of malleable metal. The orientation of the slits is perpendicular to the direction of the stretch. The result of such stretching is an array of holes on the slits – to give a mesh form. The concept emanates from the idea that metals change size – expand and contract – when subjected to various conditions. The most natural of these changes arises from the chemistry of these metals and the behavior of their atoms. This brings about the development of expanded metal. Expanded metal is distinct from, and competes with, the following: Perforated Sheet Perforation is the punching of holes, in this case, into a metal sheet. The result of such perforation is a (metal) perforated sheet. In many cases, sheets that can be perforated can also be expanded. Perforation is a subtractive process – the punching of holes implies the removal of material. This comes as a disadvantage as the removed material is regarded as wastage. Perforation does not subject the perforated metal sheet to stretching, at least not necessarily. One of its advantages is the feasibility of very small openings and drainage casings for various applications. It can also have shapes that are not feasible with other meshing techniques – this comes in handy if the mesh is intended for decorative purposes. Computer equipment often comes fitted with perforated me