Another video on this incredible magnetic field viewer: the Ferrocell.
The biggest magnets I have , monsters magnets stripped like a radiograph to reveal their secrets.
Here are the links of some interesting products provided for free by supermagnete.com
Death Magnet: https://sumag.net/death-magnet-x02
Big Cylinder: https://sumag.net/s-45-30-n-x01
Big Toroid: https://sumag.net/fe-r-100-60-20-x01
To eliminate the bubbles: https://sumag.net/q-40-10-10-n-x01