@Steve, why do you need that thing for your mouse? Don't you use a desk or something?
I do - of course I do.
But with this device, the mouse is in a much better position for comfort. As well as that, it's solved a long running problem of getting a good balance between mousing position and chair height. I'm not that tall, so either my chair is too high, so my feet don't touch the floor (I don't find footrests very comfortable), or it's too low, but then I have a lousy position for my mousing arm. With this device, instead of the mouse being forwards and to the side, it's within the natural resting position of your arm. No stretching = no arm/neck/shoulder strain, which I did get before. Not any more - which isn't surprising, as that's the purpose of the device - to alleviate arm/neck/shoulder strain.
As an added bonus, it allows me to sit back from the monitor yet still be able to reach the mouse. In fact, you can sit back completely in the chair and still use the mouse. When you need to use the keyboard, just rock the chair forwards again.
I think every office chair should come with one of these.
I know, sounds OTT, but I've done tons of research on this and what a bad arm position can lead to.
I have a mild form of RSI - had I known all this stuff ten years back, I don't think it would've developed at all.
Trust me, once you've tried using the mouse like this, you won't want to go back.