Magnetic field viewing film is a green translucent film used for viewing magnetic fields and magnetic pole patterns on a magnet or magnetic assembly.
HD Magnet Viewing Film - 50x40mm : ID 4047 : $14.95 : Adafruit Industries, Unique & fun DIY electronics and kits
EveryMarket
Magnetic Viewing Film Supplier - Magnets By HSMAG
Magnetism Discovery Bundle - Arbor Scientific
Magnetic Field Viewer Magfilm Magnetic Field Viewer Card
Magnetic field viewing film - Wikipedia
How Magnetic Field Viewing Film Works? - Magnets By HSMAG
Magnetic Field Viewer Viewing Film Pattern Display Membrane Magnetic Card Detector Magnetic Field Tools Micro-encapsulated Film - AliExpress
How Magnetic Viewing Film Acts as a Magnetic Field Visualizer < Adams Magnetic Products, LLC
50x50mm Magnetic Field Viewer Film Card Magnet Pattern Viewing Film – Star International
Master Magnetics Magnetic Field Viewer Card