When you wear magnets on the bottoms of the feet, you do not get the same results as when you put them over a major nerve path. This is the same principle when using Lidoderm patches.

This illustrates the nerves of the foot... notice they all go thru the instep on the top of the foot decending along the ankle...and this is why Lidoderm patches work well placed here:

http://www.eorthopod.com/ankle-anatomy/topic/159

Also the skin on the bottom of the foot is very thick and a barrier to everything (since we walk on it). So the insoles will not likely penetrate, as well as the lidocaine in the Lidoderms.

Ferrite magnets are quite weak and do not penetrate tissue.

All of the "medical" type magnets use neodymium magnets of 10,000 gauss to penetrate tissue better.

But you do what you want...you see to want insoles. I've worn and studied magnets and made my own pads even, over the last
decade +....so I have had alot of experience with them.
To get pain relief in my feet I tape a 1/2 inch diameter one to each side of my ankle. 10,000 gauss each. I use 1 inchers on other parts of my body for pain relief. You only need about 20 minutes with the strong ones to sedate nerves that are overfiring.

There is alot of bunkum out there... so do your research before spending your hard earned money.

Not all pain is generated in the feet, where you may feel that pain. Some may come from the dorsal roots along the spine, and some may be referred from the hip or knee, or spine.

Dr. Holcomb only used neodymium magnets for his research and product.
http://www.qmagnets.com/history-of-magnetic-therapy.php