Device invented by Professor Windish whose ray renders its victims incapable of thinking beyond the level of an eight-year-old.
A spy for KAOS steals the gun and shoots the Chief and Windish with it. She attempts to shoot 6 of the world's greatest scientists with it, but is foiled by Smart.
It is unstated but the ray also appears to erase the memory of its victim beyond the age of eight, and its effects turn out to wear off after a relatively brief period.
[Episode #7: "KAOS in CONTROL".]