You can assign any key and the 4 wheel button according to your wishes by means of software. The ball works even after 10 years still properly. That this trackball nor a USB cable which does not bother, because you - as opposed to a conventional mouse - trackball not moved. It only moves with the index and middle finger the ball. Other trackballs pursue a different approach, namely, the movement of the ball with your thumb. This has personally I am not convinced. In addition, the cable has the advantage that the trackball is constantly supplied with power and you never need a battery or battery replacement to worry.
The Trackball Explorer is ergonomically designed and the right hand rests relaxed on. Use your thumb to operate the wheel arch, wheel button and two other assignable buttons on the left of the ball and with middle and ring fingers, you can use the two buttons to the right of the ball. In my view, a very meaningful distribution.
It's a shame that Microsoft has stopped production of the Trackball Explorer some time ago. Anyway, I'm glad that I still possess a will and this use until it falls apart.