Ideal for pelvic floor exercises the ball will enhance your Pilates workout and help develop strength endurance and concentration as well as to promote relaxation and coordination. The balls are anti-slip offering excellent grip. Ball size is down to preference though it is common to have both sizes for greater diversity. Product details: Dimension - 7'' (18cm) Material - DINP PVC (Latex free) Safety - Factory tested as burst resistant at 100kg