MIKEDE Magnetic Viewing Film, 4" x 4" Green Magnetic Field Display Film, Magnetic Flux Display, Magnetic Filed Detector, Reusable and Automatic Recovery

These magnetic viewing film things are basically a much less messy way of showing magnetic force lines.The usual thing to do is use iron filings, but trust me those get extremely messy and annoying. Not only can they get scattered everywhere, but they stick to magnets and become difficult to clean off.Magnetic viewing film is similar to having microscopic versions of the iron filings suspended in a thin sheet of oil where they can show magnetic force in a similar way without being a huge mess. This makes it easy to "see" what sort of magnetic field patterns exist around different sorts of magnets and this can lead to all sorts of interesting questions.The main problem with the magnetic viewing film is that it is not very sensitive. For example, those really thin sheets of vinyl magnet material (of the sort used for cheap business promotion refrigerator magnets) show absolutely no effect on the material. A thin strip of steel with a ceramic magnet attached on one end won't show anything except around the magnet even though the steel strip is magnetized. And of course weak magnetic fields around non-wound electric wires are even weaker than that.And they can also show the presence of strong magnetic fields, such as the ones around large neodymium magnets, without having to worry about bits of metal getting yanked out of your hand or iron filings clumping all over the magnet.But the things they'd really be most useful for, like showing the magnetic field around an antenna or electric motor, they're not anywhere near sensitive enough for. They're less sensitive than iron filings on paper.Still, I'd consider them to be a useful educational tool.

It works and does what it says, however it’s mounted on a mat (like that used in picture frames) which is quite thick that you don’t get a lot of detail for smaller magnets like those in magnetic business cards. I peeled the backing layer so it was thinner, and that improved it some. I previously had a sheet of similar film that wasn’t mounted to anything, and I feel like I prefer just the sheet, no extra cover or anything surrounding it. Even with the mat frame, can get bent and damaged fairly easily.Good experience with delivery happening quickly and as expected and received exactly what I ordered.

The ferro fluid inside let's you see a picture of the magnetic field lines. Ironically I bought the bigger one & discovered there were some spots that it couldn't fit it in! You can't cut it AFAIK.

If you love magnets, this is a must