The Thermoskin® Patella Tracking Stabilizer has a fully user adjustable internal buttress that properly positions the kneecap during normal daily activities and exercise. The one piece pull-on support has been anatomically designed with the adjustable buttress and the dual Velcro strap system combining to give extremely comfortable support. The patellar opening and the adjustable buttress position the kneecap to reduce patellar mobility, which can help reduce pain from tendonitis, ligament/tendon instability, and excessively mobile patella. The Thermoskin lining will retain just enough body heat to keep muscles and ligaments loose and pliable, but will breathe so that you are comfortable during extended periods of wear. Universally designed to fit the right and left legs. Order by Knee Circumference in inches (centimeters) measured around the knee just below the kneecap with the knee slightly bent.