A first lower case member open at the top thereof supports {HEAD ~ a magnet} therein for establishing {TAIL ~ a magnetic field} oriented parallel to a central axis of the lower case 
for establishing
A first lower case member open at the top thereof supports { HEAD ~ a magnet } therein for establishing { TAIL ~ a magnetic field } oriented parallel to a central axis of the lower case
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH