The cage is set at the top of the ring, so the ball gap is pretty large in practice. I find it very comfortable, for sizing the cage I started with the rough dimensions of a standard cherry keeper cage and it worked out pretty well. For the ring I printed a bunch of basic circles to start with, each 1/8th of an inch larger than the last, so I could figure out the minimum to be comfortable long term. Then, once I had the cage done, I basically did trial and error till I got the ball gap to be comfortable. I found making the ring wider than it was tall helped make it more comfortable. It’s basically the largest I would consider unobtrusive, but it also depends on what you’re wearing over it and how you’re wearing it. When I wear it in the house I usually use a strap to keep it tight against my body, but that makes it a bit more obtrusive. Definitely the best for me of all the ones I’ve tried/made so far