The Modular Tubing with Metal Clips are used for individual exercise and stretching.รก The heart and soul of a resistance rehabilitation and exercise program. Each MediCordz Tube includes fittings and plastic clips on each end for attachment. Consists of a single section of tubing, fittings and plastic clips on each end for attachment to modular components (blue and black resistance contains metal attachment clips). Tubing stretches up to 3 times its original length. Single tubing measures 4 feet in length. Blue resistance has 14 - 34 lbs of pull.