Kensington Orbit® Optical Trackball Mouse from Posturite
Kensington Orbit Mouse - Wireless Mobile & Compact Ergonomic TrackBall Mouse for PC, Mac and Windows with Touch Scrolling, Ambidextrous Design and Optical Tracking - Red (K72352EU) : Amazon.co.uk: Computers & Accessories
Kensington Orbit TrackBall - Wired Ergonomic TrackBall Mouse for PC, Mac and Windows with Ambidextrous Design, Optical Tracking & 40 mm Ball – Space Grey (64327EU), Silver : Amazon.co.uk: Computers & Accessories
Optical Trackball Mouse - Kensington - Adapt-IT
ELECOM Left-Handed 2.4GHz Wireless Thumb-operated Trackball Mouse, 6-Button Function with Smooth Tracking, Precision Optical Gaming Sensor (M-XT4 on OnBuy