History of Kensington Expert Mouse
Kensington was famous, throughout the 1990s in the Macintosh community, for its large ball trackball. In almost all 1990s, the Kensington trackball is the coveted device for high-end Mac owners for all their graphics design needs.
Kensington Turbo Mouse 1986
Kensington Expert Mouse 1989
Ball diameter: 55 mm [see Trackball Ball Sizes and Replacement]