1.Materials: Neodymium-Iron-Boron 2.N42 3/4 x 3/8 x 3/8" NdFeB Magnet, Nickel coating 4.Certificate:ISO9001:2000, SGS, CTI ... from Neodymium,Iron,Boron and some other transitive metallic elements to make it strong. General Features: Grades:N33,N35,N38,N40 ... , Zn, white-blue Zn, Epoxy, Gold, and etc.Sizes: according to your requirementsShapes: disc, cylinder, sphere, block ,ring ,tile, arc, and ...