45-Pound pair Made of solid cast iron with a 2-inch center hole fits any Olympic bar with diameter 2 or less; Can be used with 2 dumbbell bars too All plates features a durable, black baked enamel finish to prevent the plates from rust and corrosion without any unpleasant odor Labeled in both LB and KG for easy recognition Weight plates can be used to perform muscle strengthening exercises and endurance training, or to increase flexibility and balance