Foam discs are made of Rhino Skin, a durable polyurethane foam with a tough outer coating. Will retain their original shape even after heavy use. Tough enough to use indoors out and soft enough for students and children to use for recreation or to develop hand/eye coordination. Set of six: blue, green, red, purple, orange and yellow. Diameter: 8 1/2″; Material(s): Polyurethane Foam; Playground/Gymnasium Sets Type: Foam Discs.