STRETCH ROLL / elastic tubing

STRETCH ROLL is kind of elastic tubing which replace elastic of tube with constant force spring. The spring provide equivalent strength continuously and make the equipment storage easily because it rolls back the nylon rope in the plastic ball without pulling. In plastic ball of STRETCH ROLL, there are length recorder and Bluetooth chip for recording the stretch length and transmitting the data to cell phone.
The application could suggest some effective exercise to train the muscle user choose. Then after training, STRETCH ROLL will receive the training data through Bluetooth and transfer it into a diagram.