The Cho-Pat Upper Arm Strap is recommended for swimmers and other sports enthusiasts who may develop painful biciptal or triciptal tendonitis. The strap, which is worn just above the bicep or tricep, acts as a compression device to prevent the pulling and tearing of tendon fibers. The Upper Arm Strap was specifically designed to prevent painful swimmers arm but is now used in water and other sports activities where there is a possibility of developing biciptal or triciptal tendonitis. Sizing: Measure Circumference of Arm Above The Bicep. Note: If you are between sizes, we suggest you order the smaller size.