Comfortreg; Cool Thumb CMC Restriction Splint is comfortable form fitting wraparound perforated neoprene lined in terry cloth to keep your hand cool and comfortable. When measuring for size measure palm circumference beneath base of fingers near base of thumb. Provides gentle compression that helps relieve thumb discomfort associated with CMC joint arthritis and/or instability, tendinitis or repetitive motion. Anti-microbial and Latex-free.