This unique weighted ball is a professional series ball with 2.5 lbs of sand ( lift it, shift it, impact shake,) and is Non rolling (stationary won"t roll away) for active sitting. Tones abs, Thighs, and Gluts. Increases your Cardio workout and helps with weight loss. Gym Grade-Heavy Duty. Office, studio or home use. Large opening allows for additional sand for advanced users.