the magnetic field paper is ideal for explaining magnetic fields and seeing how they interact and can change weaker fields and other little things, which helps a lot when it's not an invisible force to really show what's happening with these forces. the magnet pattern detector is surrounded by black paper picture frames, please keep it in a dry and ventilated place and avoid long time exposure to the sun as well as dark and humid conditions. It can be used as magnetic viewing film, magnetic field viewing film, magnet pattern detector, learning tool and to mess around with. visualization of magnetic fields: Excellent visual demonstration of magnetic fields. Size: inch Material: nanomaterials colour: green Package Contents: 1 set x magnetic wall mount Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.