You're Right! Clackers are the toy with a jillion names. You would put your finger in the ring allowing the marbles or balls to hang below. Here is where the fun starts. The idea was to get the two balls tapping (or clacking) against each other by pulling up on the ring lightly. Once you got the hang of it, you could get them going faster and faster until they were smacking each other above and below your hand in a stunning arc. These toys are now legendary. They started finding their way into the schoolyards in the early seventies and in 1971 were yanked from shelves because kids were suffering eye injuries when the fragile, glass-like balls were shattering from the violence of contact with their mates. I believe a plastic version may have been released after the original and the more menacing version was pulled, but I don't think that it enjoyed the same popularity. One of the main obstacles in locating this toy today is knowing what to call it. There were supposedly over 80 copy-cat products on the market during Clackers hey-day.