When an external magnetic field provides a force greater than 2.5 times the coercive force of the magnetic crystal particles, the magnetization direction of the magnetic crystal particles will be changed, and the data will be eliminated accordingly. Very safe, fast and convenient. The tools are certified by the national security authority and the military information authority. Because the MBR of the hard disk is completely destroyed, the hard disk or tape cannot be used anymore. The destruction process is recorded by Miaoyi's DDMS management system, which can be controlled end-to-end. The delivered document is an electronic version of the certificate of destruction.