Book anti-theft magnetic stripe Book anti-theft magnetic stripe; Also known as EM anti-theft magnetic stripe, the materials used are mainly composed of metal materials such as cobalt, nickel and iron. Under the action of high temperature, these metals form molten liquid, and then they are ejected from the timely nozzle at high speed to form solid strips. Because the time from liquid to solid is controlled in a very short time, an amorphous state is formed. When the distribution system is reasonable and the manufacturing process is scientific, the obtained amorphous materials have high magnetic permeability. The book burglar alarm uses its high permeability to detect and alarm. At present, both cobalt-based magnetic strips and iron-based magnetic strips are amorphous materials.