Moldable splint immobilizes CMC joint; provides heat therapy rigid support for UCL injuries associated with ball sports skiing. Helps relieve pain of tendonitis arthritis sports injuries. Rigid insert molds to shape of thumb customizes support and comfort. Comfortable for extended or overnight wear; Trioxon body wicks away moisture allows skin to breathe. Measure around wrist joint for fit. Color: Black. Size: Medium fits 61/2 - 71/2.