From the manufacturer Vinyl Standard 1-Inch Plates, 20-Pound Pair Made of thick vinyl shell filled with cement with a 1-inch center hole fits any Standard bar with diameter 1 or less All plates feature a durable, thick vinyl cover to prevent the plates from rust and corrosion without any unpleasant odor Weight plates can be used to perform muscle strengthening exercises and endurance training, or to increase flexibility and balance Sold as pairs - 5 Pounds pair, 10 Pounds pair, 15 Pounds pair, 20 Pounds pair Sold as Pairs 5 Pounds pair, 10 Pounds pair, 15 Pounds pair, 20 Pounds pair Vinyl Coated Feature a durable, thick vinyl cover to prevent the plates from rust 1-inch Center 1-inch center hole fits any Standard bar with diameter 1 or less