Same high quality latex free vinyl as the regular therapy balls, but these come with 3 little feet. The feet are a real asset when balls are used in the classroom or at home for homework. Point the "feet" down, under the ball to help keep the ball where it is placed when not being used. When ready to sit on, point the feet toward the back. They should not touch the ground. No more balls rolling around the classroom, so less chance they will be thrown. Balls with feet are really neat! 4 Sizes.