The one I linked has two tips. I never use the side with the disc, as I don't write on my Libra 2. I use the side with the large capacitive ball for tapping, so I don't constantly have to clean fingerprints off the screen. I can also slide it across the screen when I need to highlight something, but using my finger is more accurate. I just hate cleaning touchscreens.
Both sides of the pen have magnetic caps, so if you like fiddling while you read, you can snap the cap for the unused disc side on and off and drive everybody nearby crazy.
The ball side looks similar to the one Quoth linked, except the ball is silvery and looks like it has woven material in rows, whereas Quoth's looks more rubbery and smooth.