I saw this at the local sports shop and figure its a pretty casual way to get a wrist workout maybe at work, while staring at the computer monitor. Any suggested reps/sets for this ? :)

Are they good for the wrists ? Any danger ?

Thanks for the help.

Nando

I've used them to avoid another round of inflammation. I did 10 reps, then 2 different exercises with weights 15 reps each, another 5 reps. Stretch, holding for a minute on each. I did this three times a week.
Normally you wont need any more exercise on your forearms and wrists than you get while lifting.