I've been looking for a collar for a few weeks now. I keep coming across the same one showing 12mm for F, and 14mm for M. See:
I am probably not that good at translating/converting units of measurements. But what is the actual circumference of this collar? 14mm is just over half an inch, which would fit a small insect, but not someone like myself. It stands out because of the rounded edges. I don't like the blunt edged versions personally. I think I need one which is 17 inches to avoid suffocation.
Thanks.