These copper bracelets are magnetized to help heal the body and bring balance to the mind. They are very malleable so the wrist sizes listed are more of a guide than an exact size recommendation. I personally have a 7.75" wrist and wear the larger size because it wraps all the way around my wrist and touches in the back, which I like more than a cuff feel. The small size fits me comfortably as a cuff. Small: wrist sizes 6.5-7.75" Large: wrist sizes 7.5 - 8.5"