Very suitable for studying and analyzing magnetic fields, and is an interesting method for discovering magnets in objects, making it easy to locate the position of the magnets. Using magnetic nanoparticles to clearly display the magnetic field mode and intensity, it is very suitable for displaying magnetism and distinguishing between strong and weak magnetic surfaces. Observing all kinds of magnets such as neodymium magnets and flexible Magnets. Clearly view magnetic field in objects (magnetic clasp on your door, the speaker on your phone). Visualize the magnetic field lines of different objects and magnets. Magnetic field observation film is made of plastic film containing nickel iron magnetic slurry, which can clearly display the magnetization level and magnetic pole distribution. Frame can fix and protect the film, and the openings on both sides are convenient for extraction. Our magnetic field viewer is reusable and automatically recovers after use. Simply place it on the surface of the magnets to observe the magnetic field and determine the direction of magnetization. Colour:As Shown Material:Magnetic Nanoparticles Size:9x14cm (2 x 4 inch) Package Contents: 3 set x solar film