Don't quite follow Dan - if you mean the copper or magnetic ones, they are supposed to help reduce pain (arthritic or muscular)

 ........... dunno whether they work though

 If you mean the heavy 18ct solid gold ones, like mine - it just means you're minted  

Sorry, I should have been more specific. I mean the magnetic ones.

How exactly do they work?

Do not have a clue how they work.

But they work for me.