Set of 1 magnet 3" OD x 1/2" ID x 1/4" thick (76.2 mm OD x 12.7 mm ID x 6.35 mm Thick) Material: Neodymium (NdFeB) Grade: N48 Coating: Nickel (Ni) Magnetization: Axial Pull Force: 61.17 pounds SKU# M31214R OD = Outer Diameter ID = Inner Diameter NEODYMIUM MAGNETS ARE NOT SAFE FOR CHILDREN