high-quality neodymium magnet manufacturer for speakers with Dia.3 up to 220mm. Up to N52 Grade, . ... TS16949, ISO14001 Certified Product Name: high-quality neodymium magnet manufacturer for speakersFeatures:Size: φ3 up to 220mmUp to N52 max.Max ... deg. C Coating: Zn, Ni, NiCuNi, Gold, or Epoxy Applications:Speakers, esp. Mobile phone, earphone, multimedia, home and professional audio.