Unique patented design works grip, wrist and forearms | Shifting sand provides active resistance for stabilizing core muscles | Alternative to medicine balls, kettle bells, dumbbells, etc. | Safer and easier on people and floors than metal weights | Sold unfilled; simply fill with dry all-purpose sand
Unique patented design works grip, wrist and forearms | Shifting sand provides active resistance for stabilizing core muscles | Alternative to medicine balls, kettle bells, dumbbells, etc. | Safer and easier on people and floors than metal weights | Sold unfilled; simply fill with dry all-purpose sand