Price: $ - $
Aegrotatio found this for me and told me he thought I would like it. Having played games in the 80s like Centipede, Millipede and, of course, Missile Command, I was used to the track ball movement. I didn't like the normal mouse peripherals because I always rolled them off the pad, desk, etc, due to movement with graphic and photo programs.
This trackball allowed me to assign a command to each button. The scroll wheel also is a pressure button to choose/select, etc... not the best button on the unit. The ball bearings do collect dead skin, hair, and dust, which hinders mouse movement, sometimes in strange ways. "What is the pointer doing dancing around the screen?" This is easily cleaned.
Fits perfectly in the palm of my hand, allowing index-middle finger scroll with the ball, and thumb, ring, pinky button press to choose, highlight, copy, paste, and so on. As a side benefit I can go much longer with the trackball without the carpal-tunnel (sic) kicking me off of my work.
Overall the best trackball mouse available- so far...
Price: $ - $
This mouse is a good fit for your hand, but after my 3rd try, I found it useless. It works well for a day or so, but the quality of the pins inside holding the rollers to support the trackball will start breaking during week one. Week two, you will notice rust build-up on the rings as you clean the dust out with cloth or canned air. Week three finds you writing Kensington for a replacement, and week three to week four has you starting up the process again. The scroll ring is very uncomfortable with your fingers running the ball and the ring. This mouse should be avoided.