When I saw this charm I knew the name I'd give it and bead it'd have.
I give you something similar to the Sonic Screw Driver of Dr Who. Who knows if you point it and turn it on at your needles exchangeables they'll swap themselves?
The charm is, of course, on a blue bead and is a limited edition of four! Better snap that up soon, or you'll need a TARDIS to grab one.