The Jumper knee strap from Mueller helps improve patellar tracking and elevation. The adjustable strap applies light pressure on the tendon just below the knee cap to reduce the negative effects caused by frequent running and jumping. This knee band is made of neoprene and nylon with a tubular insert that helps guide the patella. It"s a must-have for athletes or anyone with knee problems. One size fits most. Ages 12 and up.