Quadrapolar Magnet Disc N30AH Zn Coating-All our licensed magnets are extremely powerful high grade Neodymium, grade N42 or higher. They are a lot stronger than normal Neodymium rare earth magnets (N30, N35, N38, or N45) on the market today.Make sure you read the magnet safety warning in the link above before you purchase or use them. Parameter: Grade:N30EH Size:24 mm X 16 mm Composition:NdFeB Magnet Coating:Zinc/Zn Shape:Cylinder/Rod/CUSTOMIZED