You are now seeing this is a non-standard multi-pole magnetic ring, a bit like a bowl shape, the other side is flat, the material is ceramic ferrite, outer diameter of 18mm, bore 4mm, thickness of 4.5mm, the use of radial multi-pole magnetization, will be divided into 16 equal parts of the ring, each 1 pole, if you need this specification you can contact customer service to provide samples, in stock.
16 pole radial multi-pole ring magnet 18x4x4.5mm ns magnetic pole distribution;
Related Special Multi-Pole Ferrite Magnetic Rings