The Polycentric Hinged Ulnar Deviation Splint™ (PHUDS) provides correction and motion control for persons with deviation of the fingers caused by Rheumatoid Arthritis. The hinges ensure free MP flexion and extension during day-time wear. Features and Benefits: Recommended for persons whose ulnar deviation at the MP joints can be corrected with mild to moderate force. The PHUDS fits the top of the hand, leaving the palm free for gripping objects. The patented polycentric hinge allows full flexion (bending) and extension (straightening) of the fingers. Softly cushioned finger stays can be opened and closed to make this splint easy to put on and take off even if your fingers are swollen. Latex-free. Moderate Control. Sizing Lay hand flat and measure width across the hand from 2nd to 5th MP (large knuckles). Choose right or left hand. Size Fits XS 2 1/4in to 2 3/4in S 2 3/4in to 3in M 3in to 3 3/8in L 3 3/8in to 3 5/8in