... 2.Various shape 3.Stable performance 4.Good corrosion resistance Ring magnets for speaker material: sintered NdFeB magnet;rare earth permanent magnetsshape ... can supply block (huge and small), thin disc, thick cylinder, ring (include sink hole), segment, tile, and ball types of ... are RoHS certified. 5) Use of magnetOur magnets are used for motor speaker, hardware, package, cabinet lock ,door lock and ...