The SrFe magnetic cores are composed of about 80% iron oxide and 20% compressed strontium ferrite and then sintered. Press forming takes place in a magnetic field. In this way, a preferential orientation (anisotropy) is determined in the magnetic core and thus a considerable improvement in remanence is obtained. Reverse magnetization at the preferred orientation is not possible. The magnetic cores below are magnetized with the preferred orientation indicated N-S. Strontium ferrite magnetic cores correspond in their hardness and fragility to a ceramic material. Machining is only possible by diamond grinding. They are insensitive to demagnetizing influences and retain unlimited magnetism. Like any ceramic material, they are insensitive to weather conditions, do not oxidize and are resistant