For a limited time receive a free 30-day trial of Daily Burn streaming workouts with purchase. Up to a $14.99 value. Sign up at www.dailyburn.com/cap. This CAP Barbell Cast Iron Hex Dumbbell can be used for both the upper body and lower body to strengthen all muscle groups. The hexagon shape of these dumbbells prevents the dumbbells from rolling, as well as provides easier storage. Each dumbbell comes in a semi-gloss finish to help prevent rusting. They are made of solid cast iron.