This is came out in .
This is a improvement over Logitech's previous Logitech Trackman Wheel.
Overall, it got positive reviews. However, compared to the classic Logitech Trackman Wheel (red ball) , the ball is a bit smaller and is a little more stiff to spin. This is also twice as expensive.
The ball diameter is 34 mm.
For replacement, you can buy at amazon
If you want a WIRELESS trackball, you don't have much alternatives.
There's Elecom Wireless Trackball Mouse. See Best Trackballs
There's Kensington Orbit Wireless Trackball, but it isn't as good.
See: Best Trackballs Comparison.Disqus