Specifically designed for osteoarthritis and medial subluxation of the thumb CMC joint. Provides gentle compression that helps relieve thumb discomfort associated with CMC joint arthritis and/or instability, tendinitis or repetitive motion. Contoured neoprene strap wraps around the thumb CMC joint and the first metacarpal for direct CMC joint support. Plus sizes are a half size bigger in the hand and a full size larger in thumb circumference to accommodate enlarged thumb conditions.