These Neodymium pot magnets feature an metric internal thread that allow them to be screwed together with objects that have a compatible external thread.
Nickel-plated Ndfeb magnets are made from an alloy of neodymium, iron & boron and are plated with a triple layer of: Ni-Cu-Ni (Nickel-Copper-Nickel) using an electrolytic based process for maximum protection against corrosion & oxidation.
The working environment of the magnetic bar determines that it must have certain corrosion resistance and high temperature resistance. Can filter out any metal impurities