The Cho-Pat is the original patented knee strap, designed to address painful overuse conditions, such as Jumper's Knee (Patella Tendonitis) & Osgood Schlatter's Disease. Its comfortable, lightweight design provides compression & support to the Patella Tendon, just below the kneecap. Can be used on either knee. Measure around the knee, just below the knee cap. If measurements indicate two different sizes, then choose the larger size. Adjusting the Velcro on the Cho-Pat strap applies pressure to the Patella Tendon. This pressure prevents maximum force being transmitted through the tendon by reducing the girth (width) of the Patella Tendon which, in turn, reduces the strain on the Patella Tendon.