Amazon.com: Kensington TurboBall Trackball (PC/USB Mac): Electronics
'via Blog this'
I used the Kensington TurboBall for years - had 4 of them, work, home, etc. Unfortunately, using mechanical rollers, eventually all jammed up beyond hope of lubrication. I replaced them with the Kensington Expert Mouse Trackball, which uses an optical sensor. The ExpertMouse doesn't jam, but its ergonomics are much WORSE than the old TurboBall - it forces my wrists to bend backwards. Therefore, here I am, >10 years later, looking to buy used TurboBalls to replace my ExpertMice trackballii.
TurboBall - the best trackball I have ever used. If it were redesigned with optical sensing, I would buy a dozen of them!
ExpertMouse Trackball - the best of the rest; the best being sold new.
BTW I have also tried the Kensington SlimBlade and the two shapes of Orbit trackballs. Plus trackballs from other vendors.
+ Ball Size - the larger the better. The ExpertMouse has a 55mm trackball, as does the SlimBlade, The Orbit has a 40mm trackball, as did the TurboBall. Since I prefer the TurboBall to the ExpertMouse, I guess wrist angle outweighs trackball size, but not by much.
+ Buttons - I really prefer 2 to 4. I think that's why I prefer the ExpertMouse to the SlimBlade. My usual bindings are LL=left mouse button, LR=right, LL+LR=middle, UL=back/forward, UR=app specific. I.e. 2 buttons just aren't enough. In fact, I use AutoHotKey to create different actions for trackball button click, hold, double-click, click-and-hold, etc. - i.e. I have 2 or more actions per button, even without modifiers.
BTW, I remember fondly an older trackball, where you could tap or depress the ball itself.
+ Ergonomics - wrist angle. The TurboBall allowed a neutral wrist angle. The SlimBlade only required a slight back angle (extension), but the ExpertMouse requires a much worse wrist extension
The ExpertMouse is so bad in this respect, requiring so much wrist backwards bend (extension), that: ...
a) I have actually used the ExpertMouse reversed - so that the part closest to me is tallest - which allows wrist flexion, a nice negative angle. It is surprisingly usable this way. It takes getting used to rolling right moves the cursor left, etc. But it makes it very hard to use other people's trackballs.
WISH: some sort of USB adapter that would negate X and Y signals.
b) If I don't manage to find a TurboBall, I will try foam wedges to adjust the ExpertMouse angle. Trouble is, my keyboard/mouse tray are not adjustable enough.