Working out with a resistance tube can be a great way to build muscle strength and tone. The FitBALL Resistance Tubing is 4ft long and is made of durable natural rubber. Foam handles provide comfort and their color follows Ball Dynamics color coded resistance level system. They can be used for a variety of fitness and exercise routines. The FitBALL Resistance Tubing is available in extra light, light, medium, heavy, and extra heavy resistance levels.