... loudspeakers,invisible magnetic button and invisible magnet and other uses of magnets Material Grade of NdFeB magnet: Magnet N-( N35, N38, N40, N42 ... , N45, N48, N50,N52), Magnet M-(35M, 38M, 40M, ... -(30SH, 33SH, 35SH, 38SH, 40SH, 42SH), Magnet UH-( 28UH, 30UH, 33UH, 35UH, 38UH), Magnet EH-(28EH, 30EH, 30EH, 33EH, 35EH) coating: ...