This tool, a twin-jet electro-polishing system, embodies a long-standing, well established, and efficient method to prepare thin foils for transmission electron microscopy from metals and alloys. A thin disk of the specimen metal obtained from the grinder-polishing tool process may be brought to this apparatus where it is subjected to an erosive attack by an applied electric current simultaneously combined with the action of a chemical etchant. The process is essentially a controlled corrosion of the metal, which results in a metal foil of sufficient thinness that the electron beam in a TEM can penetrate through the sample to produce an image. The tool pictured above uses a cooling water system to maintain a constant temperature of the corrosive electrolyte solution. A temperature as low as -40°C can be achieved and maintained using this system. (Image: Struer TenuPol-3 electro-polisher).