The Carpel Tunnel Brace with Thumb Spica by Thermoskin is a removable palmar splint with locking strap and thumb spica, providing superior bracing for wrist/hand and thumb related injuries, including Carpal Tunnel, RSI and skiers thumb. Thermoskin products all have a patented Trioxion lining made of a spiral-like material which stimulates the skin and creates the heat required for healing while allowing the skin to breathe and minimizing discomfort. This brace is most often used for: Carpal Tunnel Syndrome Collateral Ligament Injuries Lateral Ulnar Ligament Injuries Carpometacarpal Joint Injuries Sizing: Measure evenly around the wrist joint. XSmall 11 - 13 cm 4 1/2 - 5 1/4 in Small 14 - 16 cm 5 1/2 - 6 1/4 in Medium 17 - 19 cm 6 1/2 - 7 1/2 in Large 20 - 22 cm 7 3/4 - 8 3/4 in XLarge 23 - 25 cm 9 - 10 in XXLarge 26 - 30 cm 10 1/4 - 11 1/4 in