I remember Clackers. Look at that tiny little metal ring. It was easy to lose control of that and send those Clackers flying through a window or knocking someone’s head off or doing other types of serious damage.
Fun toy. Until someone loses an eye.
I clacked many a Clacker!......................
Had a couple pairs towards the end of elementary school. While they could well be rather painful until mastered, I never saw any shatter...