The McDavid PSII Bi-Lateral Geared Polycentric Hinged Knee Brace Support is engineered to enhance medial and lateral stability, making it a great choice for those recovering from MCL and ACL injuries.(Small Size)Bi-lateral geared polycentric hinges for stability and free movementFor Recovering from MCL and ACL Injuries; Padded Buttress for Patella Support; Bound EdgesSmall 13" - 14", measure knee circumference at center of knee, stand and bend your leg just less than 45 degrees, measure knee circumference 2" below the center or patella (kneecap)Hook and Loop Closure; Seamless and Perforated Back Panel; Heavy-Duty Nylon Outer LayerLatex-Free Neoprene; Fits Both Left and Right Knee; 100% Latex-Free 4.8mm Neoprene