Exercise ball a chair because of ergonomic considerations or biomechanical reasons. This large plastic ball, known as a "birth ball", can also be used during labour to aid the descent of the fetal head into the pelvis. Sitting in an upright position will also aid fetal positioning and is more comfortable for the woman. Sitting on the ball with arms placed on a bed, table or otherwise sturdy object for support and gently rocking the hips may help the woman during contractions and aid the natural physiological process of birth. Exercise ball An exercise ball, also known as a Swiss Ball, is
Nine-ball in a diamond-shaped configuration, with the 1 ball positioned at the front (toward the position of the breaking player) on the , and the 9 ball placed in the center. The physical rack used to position the balls is typically triangle-shaped, usually wood or plastic, and capable of holding all fifteen object balls, although diamond-shaped racks that hold only nine balls are sometimes used. The placement of the remaining balls is generally considered to be random. However, in some tournaments, the ball being to the lesser player must be one of the two balls placed behind the 1 ball at