Shape: DiscSize: 12mm x 3mmHole Size: 4mmMaterial: NdFeB permanent MagnetsGrade: N40Max Working Temperature: 80°C/176°FTolerance: +-0.8mmPlating: Nickel + Copper + Nickel Triple Layer PlatedPackage Include: 10 Pcs/LotNote:1: Neodymium magnet is extremely powerful, pls take care of your fingers or other body parts to avoid injured between 2 pieces big magnet;2: Neodymium magnet is very fragile & easy damaged, pls handle gently;3: The max operating temperature is 80°C/176°F.