Another thing that I love about this body is the grip. It's a fat, textured grip that feels good in my hand when writing. It also does a really good job of resisting lint and dust.
The "knocks" for each color are a bit weak, but that's normal for any multi pen. There just isn't much space to include high-quality, sturdy knocks for each cartridge. Yes, some more expensive multi pens have much more sophisticated designs that feel and work great, but they don't cost less than $10 like the Acroball 4.
I went with a clear body, which I'm really happy with. I have a soft spot for demonstrators, and this one fits the bill. There are a few other color options, but most of them feature a partially clear body. The colors only take over the grip and clip pieces on most options. The black one is just...black, and the blue one has a blue transparent body.
The Acroball is a great writer. Pilot has a really great cartridge here, and I'm happy to use it. But, it just isn't as nice as the Jetstream cartridges. In my experience, the Acroball skips a bit too much when compared to the Jetstream. The colors work well, but the black is a little lighter than I prefer.