In one of my recent JetPens purchases, I added the Pilot Frixion Ball Knock .5 . Before this pen, I had never tried anything in the Frixion line of pens, but I've heard good and bad things, both of which ended up being true.
If you click for a larger view it will be easier to see how the ink is not really black. I still enjoy the color of the ink, but I think it should be labeled accordingly (Shadow Black, Pencil Black, etc.)
The rubber ball that "erases" the ink is very effective. The ink is thermo-sensitive, so it disappears with heat (and can reappear with cold).
The barrel is only moderately flashy. I think the graphic borders on being too "loud" for my tastes, but at least it is small.
My biggest gripe is the clip. The plastic feels brittle, and the clip itself rattles as you write. It is not unbearable, but it is annoying.
The point and grip both remind me of the Pilot V-Ball, which is good. The grip is comfortable and the writing experience is solid.
Is it just me, or does this look a bit like a little robot?
So, how well does the ball make the thermo-sensitive ink disappear?
Very well. All you can see is the indention on the page and some faint ghosting when you look closely. It's so much better than the crappy erasable pens I used in elementary school.
I did enjoy testing out the Pilot Frixion Ball, and I will be looking to try other models to see if I like them better. Either way, the black ink still needs to be darker and, well, black.