It's a flexible, heavy-duty, rubber tube, encased within a soft fabric cover. The Bands' dynamics act to alter the effects of gravity. As group members develop trust in the Band and one another, they are encouraged to take those small risks that, once accomplished, help build individual, physical and emotional confidence. Children (adults, too) stand within the band and push outward until they reach a state of stability. Outer material: 100% Cotton. Inner material: Rubber. Up to 6 to 12 children.