This Labradorite tension cuff is a circumference of 6 1/2th on the inside. All you need to do is push the sides of the cuff in slightly and it will unhook. It is the same simple process to put it on one handed!
I have a tinny wrist and though it is lose on me it is comfortable and safe. It will not slide off.
This can't be adjusted due to the size of the stone on top.