The green/black GoFit 4lb medicine ball (Item GF-MB4) is perfect for athletic training of all types. These balls are sturdy enough to bounce against the hardest surfaces and retain their shape. This new basketball-style ball is perfect for core training with a partner or by yourself with a rebounder or against a wall. Includes a DVD training session by Mark Verstegen, trainer for many top athletes in all sports. Also included is an exercise poster.