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