The product you see now is a thin ring magnet with more than 100 poles, 128 poles in the outer ring (64 N poles, 64 S poles), 126 poles in the inner ring, belongs to the double code channel multi-pole magnetic ring, the material is rubber magnet, so the magnetism is not strong, the surface magnetic strength is only a few hundred gauss, suitable for magnetic induction encoder, magnetic ring encoder.
128-pole and 126-pole flat magnetic rings on one side
Recommended specifications for related multi-pole magnetic rings;
Multipole double coil rubber magnetic ring for encoder D49x25x2mm