SET OF 4 (each 5 lbs., TOTAL of 20 lbs.) - Made of solid cast iron and coated in a gray baked enamel finish to prevent chipping and peeling; Ground edges and machine center hole ensure a standardized product; Standard plates have a 1 inch center hole to accommodate standard bars VERSATILE - Weight plates can be used to perform muscle strengthening exercises and endurance training, and to increase flexibility and balance. These weight plates can also be used for warm up exercises