Funny you noticed that - it’s a little slot that holds on to a pack of rolling papers, and the Dyna just happens to fit perfectly in there (the silicone of the Dyna “B” has just enough give that it kind of “pops” into place like it was made for it).

It’s a great way to carry it around the house and a secure place to keep the Dyna while it’s cooling off. I’ve had this grinder for years, the fact the Dyna fits perfectly is total dumb luck.