Thera-Band Latex Exercise Bands are available in colour-coded levels of resistance. Proper use of these systems for resistive exercise provides both positive and negative force on the muscles, improving strength, range of motion and cooperation of muscle groups. Colour-coded progressive resistance gives at-a-glance documentation of progress from one level to the next. With Thera-Band resistive exercise systems, measuring progress and achieving goals for fitness or therapy is easier than ever before. Different resistance levels are determined by thickness of the band. This comprehensive system provides positive reinforcement and feedback for gauging results.