No antennas involved, and no strings (if you mean like guitar strings or similars) ..... it have something to do with electric machines, but only in a very indirect way, and does not include any electric element itself, nor it need electricity for work (oh, come on, it's really easy this time ..... just look at its shape )
Another little help ..... think about the letter "S" (but not for the name).
30 to 50 %, i think ..... i have seen them at least 10 times ..... it depend how much electrical apparates you may have dismantled in your life (oops, i've said too much, now )