Thera-Band Tubing is available in a range of six colour-coded levels of resistance Proper use of the Thera-Band system for resistance exercise provides the user with both positive and negative force on the muscles, improving strength, range of motion and cooperation of muscle groups. The colour-coded progressive resistance levels, allows clear, structured and visual documentation of progress from one level to the next. With Thera-Band Tubing, measuring a user’s progress and achieving goals for fitness or therapy is easier than ever before. The different resistance levels are determined by the thickness of the tubing in use with the clearly colour-coded levels increasing in difficulty from the easiest Yellow (Light), to the hardest, Silver (Super Heavy). This comprehensive system provides positive reinforcement and feedback for gauging results .