magnetic field viewer watch movie 50x50 mm map magneet detector pattern display 40ja

description: ootdty characteristics: 100% new and this item is easy to use. just place the map on the surface of the magnetic material and it will reveal a magnetic field of pattern. great for personal or scientific research. and it helps us study magnetic fields that we can't see. it can be used for quality control, product demonstration, reverse engineering, authentication and educational purposes. compact and portable size, lightweight, handy to carry. great educational t