Exercise & strengthen muscles in the upper & lower body to build strength, increase motion and improve conditioning Improves strength, range of motion and flexibility in a simple to use, portable product that works in the clinic, the gym, at home or on the road Color-coded Progressive Resistance system allows users to recognize improvement as it happens, as you grow stronger you can move up to the next color Rehabilitate muscles through simple yet effective workouts to increase strength & improve motion Heavy Green Tubes are the fourth of eight levels of resistance and great for rehabilitation and light to moderate resistance exercise, they offer 4.6 lbs. resistance and 25% increase from preceding color at 100% elongation, and 6.7 lbs. at 200%