X-Trac™dual strap knee support: Stabilizes patella, improving patellar trackingX-shaped wrap applies compression above and below knee.Support for recovery from patellar and quadriceps tendonitis as well as patellar tracking disorders that may cause chondromalacia and patella femoral pain.Premium quality materials enhance comfort and durability. Sizing Chart Measure circumference 1″ above the top of patella (knee cap).