Kensington Expert Mouse - Wired Ergonomic TrackBall Mouse for PC, Mac and Windows with Scroll Ring, Ambidextrous Design and Optical Tracking - Grey (64325) : Amazon.co.uk: Computers & Accessories
Kensington Expert Mouse Optical - Trackball Kensington on LDLC
Amazon.com: Kensington Expert Trackball Mouse (K64325), Black Silver, 5"W x 5-3/4"D x 2-1/2"H : Everything Else