Durable rubber core elastic exerts compression over the soft tissues of the knee, fitting comfortably around the bony prominences of the joint. Encircles the ankle like a bandage but without the bulk. Absorbs perspiration for all day wearing comfort. Fits easily inside shoes - can be worn on either right or left ankle. Measure around the smallest part of the ankle. Available Sizes: Small (6.75-7.75 Inches), Medium (7.75-8.75 Inches), Large (8.75-9.75 Inches), and X-Large (9.75-10.75 Inches).