Sintered NdFeb permanent magnet materials are divided into six types of products according to the coercivity of magnetic pole strength: low coercivity (without letters), medium coercivity M, high coercivity H, extremely high coercivity SH, ultra-high coercivity UH, extremely high coercivity EH.
Alnico magnet is the earliest developed permanent magnet material, which is an alloy composed of aluminum, nickel, cobalt, iron, and other trace metal elements.