1. DEVICE COMPRISING A MAGNETIC CIRCUIT INCLUDING A PAIR OF NORMALLY OPEN SWITCH CONTACTS OF A MAGNETIC MATERIAL TOGETHER WITH AT LEAST TWO SEPARATELY MAGNETIZABLE BODY PORTIONS, EACH OF SAID PORTIONS HAVING A MAGNETIC FULLNESS RATIO OF AT LEAST 50 PERCENT AND EACH OF SAID PORTIONS CONSISTING ESSENTIALLY OF AN ALLOY CONTAINING FROM 40 TO 75 PARTS BY WEIGHT COBALT, 25 TO 60 PARTS BY WEIGHT IRON, AND 1 TO 5 PARTS BY WEIGHT VANADIUM, SAID BODY PORTIONS HAVING BEEN PRODUCED BY A SERIES OF PROCESSING STEPS TERMINATING IN A COLD REDUCTION OF AT LEAST 60 PERCENT, FOLLOWED BY A PARTIAL ANNEAL DURING WHICH ANNEAL THE SAID BODY PORTIONS ARE MAINTAINED AT A TEMPERATURE OF FROM ABOUT 400 TO 675* C. FOR A TIMER PERIOD OF FROM ONEQUARTER TO 25 HOURS, THE SHORTER TIMES CORRESPONDING WITH THE HIGHER TEMPERATURE, THE SAID BODY PORTIONS BEING MAGNETICALLY BISTABLE, THE ARRANGEMENT BEING SUCH THAT CLOSURE IS ACCOMPLISHED BY MAGNETIZATION OF BOTH PORTIONS IN SUCH DIRECTION THAT THE LOWEST RELUCTANCE MAGNETIC CIRCUIT INCLUDES THE TWO PORTIONS AS WELL AS THE SAID SWITCH CONTACTS, THE REMANENT FIELD OF THE SAID PORTIONS BEING OF SUFFICIENT STRENGTH TO OVERCOME THE NORMAL FORCE MAINTAINING THE SAID SWITCH CONTACTS OPEN SO THAT CLOSURE IS MAINTAINED, AND IN WHICH RELEASE IS ACCOMPLISHED BY MAGNETIZATION OF ONE PORTION IN A DIRECTION OPPOSITE TO THE RESULTING IN CLOSURE.