The Drytex Hinged Knee Suppoprt Is A Neoprene Alternative Constructed Of A Unique Nylon Core And Polyester Lycrar Fabric That Allows For Improved Airflow Provides Compression And Support Yet Allows For Breathability Ideal In Warm Weather Climates Designed For Mild To Moderate Medial Lateral Stability Measurements Taken 6 Above Mid-patella Knee Joint Line And 6 Below Mid-patella Circumference Extra Small Fits: Thigh: 13 - 15.5 (33 - 39 Cm); Knee Center: 12 - 13 (30.5 - 33 Cm); Calf: 10 - 12 (25.5 - 30.5 Cm)