Fortress Premium Plus exercise bands are high quality, used in the rehabilitation and strengthening of joints in the musculature system. These exercise bands come in varying grades of resistance marked by colour, ranging from easy to super heavy resistance. Light colours = light resistance (yellow, red, green) and dark colours = heavy resistance (blue, black, silver). Each band comes in a 45.5m roll perfect for professional physiotherapist studios or gyms. Simply roll out, measure and cut for individual use.