A device for measuring any non-magnetic coatings (paint, enamels, chrome, etc.) on ferro-magnetic bases (e.g. constructional steel, car bodies, etc. )or measuring any non-magnetic coatings (paint, enamels, etc.) on ferro-magnetic bases (e. g. constructional steel, car bodies, etc.) as well as for measuring insulating coatings (e.g. paint, enamels, anodic films, etc.) on non-ferrous metal bases (e. g. aluminium, copper, brass, etc. )