20Pcs Ferrite Toroid Cores Set Transformer Inductor Coil Ring Black For Power Transformers Current Transducers Inductors Toroidal cores are passive electronic components consisting of a circular ring or donut-shaped magnetic core of ferromagnetic ferrite around which wire is wound. Specification: Color: Black Material: Nickel Zinc Ferrite Squareness Ratio:10 Bs: 400T Br:150mT Tc: 120C Hc: 13A/m :4.9g/cm3 i:650-1000 A: Outer Diameter: 9.5mm/0.37 inch, 10mm/0.39 inch, 11.5mm/0.45 inch, 12mm/0.47 inch, 14.2mm/0.56 inch Inner Diameter: 5.5mm/0.22 inch, 6.5mm/0.26 inch, 5mm/0.2 inch, 7.3mm/0.29 inch, 8mm/0.31 inch Thickness: 14.5mm/0.57 inch, 20mm/0.79 inch, 25mm/0.98 inch, 15mm/0.59 inch, 28.5mm/1.12 inch B: Outer Diameter: 10mm/0.39 inch, 14mm/0.55 inch, 16mm/0.45 inch, 16mm/0.63 inch, 17.5mm/0.69 inch Inner Diameter: 6mm/0.24 inch, 8mm/0.31 inch, 8mm/0.31 inch, 9mm/0.35 inch, 9.5mm/0.37 inch Thickness: 10mm/0.39 inch, 7mm/0.28 inch, 16mm/0.63 inch, 28mm/1.1 inch, 28.5mm/1.12 inch C: Outer Diameter: 17.5mm/0.69 inch, 18mm/0.71 inch, 20mm/0.79 inch, 22.5mm/0.89 inch, 25mm/0.98 inch Inner Diameter: 9.5mm/0.37 inch, 10mm/0.39 inch, 10mm/0.39 inch, 13.8mm/0.54 inch, 15mm/0.59 inch Thickness: 12.7mm/0.5 inch, 10mm/0.39 inch, 10mm/0.39 inch, 10mm/0.39 inch, 12mm/0.47 inch Packing List: 20 x Toroids (4 Pieces For Each Size) Advantages: Ferrite cores are dense, homogeneous ceramic structures made by mixing iron oxide (NiZnFe2O4) with oxides or carbonates of nickel, zinc. Have very high permeability and low losses, can work at high frequencies. Instruction: Used to suppress electromagnetic emissions by blocking low-frequency noise and absorbing high-frequency noise, avoiding interference. Widely used in EMI/RFI filters, audio transformers, communications, control circuit equipment, LED lighting, automotive electronics, industrial control, etc. NOTE: The more the number of coiled cables, the better the effect of suppressing interference with lower frequencies, the weaker the effect of suppressing noise with higher frequencies.