In an advantageous form of construction, the dial has at least one magnet, which by rotation of the dial is guidable along {HEAD ~ the sensors} realized in {TAIL ~ the form} of field probes 
In an advantageous form of construction , the dial has at least one magnet , which by rotation of the dial is guidable along { HEAD ~ the sensors } realized in { TAIL ~ the form } of field probes
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH