They don’t work.
Don’t be gullible. Don’t fall for them. There are no health benefits from wearing magnetic insoles. All sorts of nonsensical claims about them affecting energy balance (what ever that is), pain relief and improving the circulation get made for these. They simply do not work. Several studies have now shown that they are no better than a placebo or sham insole. All of the claims made for them are simply nothing more than magical or wishful thinking.
Oh, and if you have tried a magnetic insole and think you got better from them, then that was because that was just the natural history of your problem or the use of expensive placebo – or it might have been because of some arch support or cushioning of the insole. It was not because of any magic or mystical force from magnetics.