Permanent magnetic hook (Holding magnets) are made from different kinds permanent magnets and metal or plastic pot as per requirements . Special magnetic circuit make it have super strong magnetic force , many times stronger than the single strong magnet.
Material of metal pot: Copper, Aluminium, Steel, Plastic..
Material of magnet: NdFeB, Ferrite, AlNiCo, SmCo...
Coating : Nickel, Zinc, Epoxy, Cr, colorful Painting (black, white, blue,red... Rubber...