Use the Gymnic balls for gymnastics, exercise and balance therapy. Each ball is fabricated from the thickest formulation of fine vinyl, using the seam-free roto-molding process. No seams means there is almost no chance for the ball to leak. Each ball features raised latitudinal ribs for easier grasping and control. GYMNIC BALLS SHOULD BE USED FOR BODY WEIGHT EXERCISE ONLY AND ARE NOT SUITABLE FOR BENCH PRESS EXERCISES OR USE WITH ANY KIND OF WEIGHTS IN ORDER TO AVOID ANY POTENTIAL INJURIES TO USERS.