[0kama]

Alright, I was bored and I flipped my APM over and looked at the red light(yes I was that bored), then I noticed that there is something around the eye that you can turn, left, right, or center. What the hell is this thing and what does it do?

[OpenStep]

I think it has something to do with how stiff the clicker is... I dunno though cause I can't notice a difference if I turn the dial and try clicking.

[geekwagon]

It sets the sensitivity of the optics, effectively speeding up or slowing down the mouse pointer, IIRC.

EDIT: Oops, just googled it. I just assumed it was for the optics but OpenStep nailed it.

[tooki]

Yep, it's the button tension.

That said, nobody ever bothered to use that feature, so the latest Pro Mice don't have it any more.

tooki