"Three stickers would fill the whole side of your helmet, that's how big they were," Nein said. "They were tennis ball-sized stickers." In 1969, Michigan hired Schembechler and he brought his ...

What are tennis balls made of? Modern tennis balls are made of a hollow rubber core, covered in a wool or nylon shell which is known as the nap. Pressurised air inside the rubber core makes the ball ...