The device includes a pair of toroid magnets each having {HEAD ~ a north pole} and {TAIL ~ a south pole} 
The device includes a pair of toroid magnets each having { HEAD ~ a north pole } and { TAIL ~ a south pole }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL