Nerfuls were a line of 3-inch ball-based figures, made by Parker Bros between 1986-1989. Each basic figure was made up of three interchangeable pieces (body, head, and hat/hair). Nerfuls only lasted one series including playsets and vehicles, and though at least one other wave was planned and partially produced, it never saw retail sale.
Nerfuls are one of my favorite toys ever, and I have spent a great deal of time building my collection, and searching for rare pieces.