The MediCordz Modular Tubing is used for individual exercise and stretching.áThe 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 tube comes 3 feet in length. The Black resistance has 20 - 45 lbs of pull.