The ball allows - compared to the role - a wonderful and very effective localized treatment of tension in the cross. I lie in bed and lie down with the strained point directly to the ball. Then I move a little back and forth. He then presses the exact center of the tension as it would make a massage with the thumb. In addition to a tennis ball and a hard floor is quite good, even better two together in a sock.
The door frame I press the ball on the strained and shortened muscles between the neck and shoulder. The correct position is not easy to find, but then it hits and pulls and stretches properly. If I do not already have it, I would buy it to me.