On back: "ELECTRIC GUARDIAN--This simple little gadget, pointed out by J. J. De Moore, California Street Railway superintendent, gives warning if the cable has a broken wire. If even one of the 104 steel wires in the cable breaks, the frayed end touches the ring through which it passes and sets off an alarm. Then the cable has to be repaired with a 60-foot 'long splice' so skillfully done that the diameter of the cable is not changed at the splice."
