Scientific, surveying, optical, weighing, measuring, signalling, life-saving and teaching apparatus and instruments, apparatus and instruments for conducting, in particular cables, switching, transforming, accumulating, regulating or controlling electricity and electromagnetic waves; apparatus and instruments for protection against the influence of electrical and magnetic radiation and electromagnetic waves; apparatus for recording, apparatus for transmission and reproduction of sound or images, magnetic data carriers, gramophone records, mechanisms for coin-operated apparatus; cash registers, calculating machines, data processing equipment, computers; fire-extinguishing apparatus; filters for radio interference suppresssion.