neodymiun magnet: a): Grade can be N52,N50M,etc b): 21 years ... ,Zn etc Details about our neodymium magnet:a/ Our capacity of production:NdFeB magnet: 2160T/yearHard ferrite magnet: 6000T/yearb/ Size: many moulds ... Zn, Zn3+Cr, gold, sliver, epoxy, phosphate, passivate.d/ Grades: N35-N52, N35M-N50M, N30H-N48H,N30SH-N45SH, N30UH-N40UH,N30EH ...