Hard ferrite is made by ceramic process method and sourced from SrO or BaO and Fe2O3. It is cheaper than other magnets because of lower price for raw material and simpler production. Oxide is the mainly composition of ferrite, so it has no need to electroplating as they don’t suffer from environmental or chemical substances (except the acid) corrosion. They mainly used in crafts, adsorption pieces, toys, motor, speaker, etc.
There are USA Standard, Chinese Standard and European Standard.