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. Color-coded progressive resistance gives at-a-glance documentation of progress from one level to the next. Thera-Band Resistive Exercise Systems cost much less than other exercise equipment sold with claims of achieving similar results, plus they are portable and versatile with virtually unlimited uses. Recognized and used throughout the world, they are endorsed by the American Physical Therapy Association (APTA).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 or the tubing. And we designed the Thera-Band Progressive Resistance System with color-coded levels increasing in difficulty from tan to gold. This comprehensive system provides positive reinforcement and feedback for gauging results.