N42 disc permanent ndfeb magnet 1.grade: N35-N52,(M,H,SH,UH,EH) 2.ceritfication:ISO9001:2008 / SGS 3. ... magnets,Sintered Ndfeb is the strongest permanent magnets in the world up to date,It has excellent properties of high remanence ... your test. N42 disc permanent speaker ndfeb magnet N35-N52,(M,H,SH,UH,EH)