The measuring mechanism consists of a current coil wound around a fixed iron and a moving iron mounted with the pointer on the system axis. The system is mounted on tip bearings and damping is provided by silicone oil. The beginning of the scale is compressed, which enables linear reading from approx. 15 % of the measuring range. Ammeters have a display range for twice the nominal current (100 % overload). The overload range of the scale is strongly compressed and has only a few scale lines. The accuracy class indicated in the toolbar basically refers only to the part of the nominal scale range marked by a start and end point. For voltmeters, the measuring range is continuous (without overload range). The special housing design allows a quick exchange of the interchangeable scale. This is particularly interesting for instruments that are to be connected to current or voltage transformers (xA/1A, xA/5A, xV/100V, xV/110 V).