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. Features 7" Exer-Soft Ball (18cm). Ideal for pelvic floor exercises. Enhance your Pilates workout. Help develop strength, endurance, and concentration. Promote relaxation and coordination. Anti-slip offering excellent grip.