These custom ferrites are made of a special high-frequency material and uniquely modified to help prevent high-current saturation. A ferrite is
EMP Whole-House Ferrites
Ferrite core with plastic case, Magnetic components, Transformer, Inductor, Choke Manufacturer
Ferrite • Advanced Magnet Source
50Ω, 0.3A chip ferrite bead, Magnetic components, Transformer, Inductor, Choke Manufacturer
EMC ferrite cable clamps Holland Shielding Systems BV
61-Material NiZn Ferrites - Fair-Rite Products
Ferrite rings
2861010002 Fair-Rite, Fair-Rite Ferrite Core, 255-5119
How Do Ferrite Beads Work and How Do You Choose the Right One?, PCB Design Blog