Ring magnet of all gardes ,such as N35-N52, N35M-N48M, N35H- N45H, N35SH-N42SH, N28UH-N38UH and N28EH-N35EH, which are widely used in trades and fields such as electric motors, electric generators, nuclear magnetic resonance, magnetic levitation, magnetic separators, electronic equipment, toys, instruments and meters, electro acoustics and patent technologies.