I used to work at a place that sold them, the Lyceum used to be supported by a company that sold them
As well.
One that was intersting was just a pair of glasses with amstraw attached to them so you could blow into them while looking at the sun. created rather the same effect.
This is nothing new. Benjermin Franklin discoverEd that when electric charge was put near eyes or head images where produced. Over time
We discovered this is a phenomena called entoptic imagery. There are lots of ways to produce this entoptic imagery, dmt, drugs, sleepmdept, sleep,'magnets, electricity, any form of altered state. So a magnet helmet does it? Somewhat somdoes pressing on your eye balls. some methods are more
Effective then others. Mind machines really do the trick though, just like drugs but without he ego disolving and euphoria.