Compression Sleeve with Open Patella in a comfort flex design, Anatomical Precurved Compression Fit Sleeve Design, Breathable Mesh Window, No-slip Silicone Gripper Pattern Lining, Convenient Finger Tabs offer easy grip pull when fitting, Lycra Binding for comfort and long lasting wear, N-Tex Vented Neoprene, Measure knee circumference 2" = 5cm below center of kneecap (patella), Size Small Knee Inches 12.25–13.25, Knee CM 21.1–33.7