... many grades:N35-N52, 33M-45M,30H-45H etc. Annular NdFeB magnet Shape: Arc(segment),Block,Cube,Cylinder,Disc,Ring,Rod,SphereMaterial ... .Coating:Zn,Ni,NiCuNi, Au,Passivation Application: NdFeB magnets are generally used for motors, speaker, toys and electronics, sensors, transformers, winding machines ...