An adjustable ring also called a free-size ring, is a ring that isn't closed to allow you to adjust and expand the ring to about half a ring size.

So, if you are looking for a ring and your finger is technically a size 10, but you have bigger knuckles (due to arthritis, etc), you’d probably love an adjustable ring because it can expand slightly, fitting over your knuckles easily. This makes them significantly more versatile than the traditional rings,