Sperry's friends became test subjects, playing with early iterations of Gyrings in school. These preliminary models came came in several sizes, ranging from one to three inches in diameter, but had sharper corners on the insides of the rings. "I knew I could improve the design, because it kind of hurt when you used it," Sperry admits. "Everyone else had a similar reaction. They were like, 'Whoa, this is cool! It sucks, and you can make it a lot better, but this is cool."