u/Radiant-Ability5814

Just bought a tugger but realized that there are larger sizes available; I think my current 16mm one is too small, but I’m not sure how to tell. I measured myself at 19 mm, should I go up to 20 or to 18? I’m not even sure if my measurements are right, it’s so hard to do, and I’ve gotten different numbers several times. Also, can I just buy the external sleeve and use my current bell, or do I have to purchase an entire new tugger?