The Berthold Test is used to determine the magnetising efficiency. The central piece is cut into quadrants to provide indications at 0 and 90 degrees. It is composed of a circular central part in ferromagnetic material in the shape of a cone, with the cuts perpendicular to each other. This cylinder-shaped part is inserted on the metallic base, so that it can be rotated around its axis in order to modify the distance between the surface and the plate.