The B4 Play Ball is essentially a rubber ball made from monoprene (elastomeric polymer) with small, protruding pimples on the surface to stimulate the skin, during use. The compression factor is very specific and consistant, not being too soft nor too hard, as in the case of a GOLF BALL, which is too hard and too small or a TENNIS BALL, which loses compression and is too soft. These two balls are certainly not designed as massage tools.
The B4 Play Ball has a silicone rubber tubing inserted through a central hole to prevent it from rolling away, when in use, especially while on a long-distance flight. This tubing is simply twisted around the ankle to secure the ball under the user's foot. The tubing is non-toxic and virtually unbreakable and can be used for various other exercises (like a thera-band). It is possible for the user to detach the tubing from the ball if it is uncomfortable or to shorten it's length.