Ferrite magnets are a ceramic material which made by mixing and calcining large proportions of iron oxide blended with small proportions of one or more additional elements. Besides holding applications, the most representative application of ferrite ring magnets is the loudspeaker. Regular ferrite ring magnets are magnetized via axial direction, and actully, SDM also can provide diametrically magnetized, multi-pole magnetized, and uni-pole magnetized ferrite ring magnets.