Initially, I was skeptical about the cute little grip and rollstop that Tom's studio put out for the Lumos Pro pens, but now I'm absolutely thrilled with having it. It's probably one of the most useful accessories I have for the Lumos. Absolutely necessary. Absolutely wonderful. And pretty cute, too.
The initial reaction I had to it being cork was part of the problem. I thought the leather ones would be a little more nice. But it turns out the cork grip and rollstop feels just really really good in the hand. As well as, of course, stopping the pen from rolling off all my desks (nothing is level around here it seems).
Don't go without it!