If you have the wrong polarities, you can get sick within hours. Nonconductive brace creates little energy loss for the magnetic device. You can use ceramic or rare earth magnets. You can find ceramic magnets in every hardware store. Since it is an eternal life device, it's better to purchase good quality, powerful magnets for the sake of your great health .
Rare earth is a little more expensive, but they are much more powerful than ceramic.
I recommend rare earth magnets. I always use the best quality magnets to build my devices. Slide your foot into the brace. Catch the strap with your big toe and your index toe of your foot. Also wear the foot braces during sleep.