Tone and strenghten muscles without the hassle of changing weights and plates. Simply chose the resistance that is right for you and work out anywhere anytime. Add to an aerobic workout to enhance toning and overall fitness. Made of Latex Rubber. Long Band is 45 to 50 inches in length. Six different colors represent six different resistance strengths. Blue = Very Low Purple = Low Yellow = Medium Green = Medium Plus Red = High Black = Mega