Clackers
Clackers (also known as Clankers, Ker-Bangers, latto-latto in the Philippines and most of Southeast Asia, and numerous other names) are toys that were popular in the late 1960s and early 1970s.
In 1968, tempered glass sphere models emerged that could eventually shatter and injure users or others nearby. In the early 1970s, manufacturers changed them to plastic spheres suspended on each string. When they were swung up and down, banging against each other with a lot of force they made the loud "clacking" sound. Clackers are similar in appearance to bolas, the Argentine weapon.
The toy is formed out of two solid balls of polymer, each about 2 inches (5 cm) in diameter, attached to a finger tab with a sturdy string. The player holds the tab with the balls hanging below and through up-and-down hand motion makes the two balls swing apart and back together, making the clacking noise that gives the toy its name. With practice one can make the balls swing so that they knock together both above and below the hand.