Old hard drives are good sources of strong rare earth magnets.

[Peter C.]

When using magnets you need a piece of ferrous metal for the magnet to stick to, like a washer or something. When the magnet is stuck to the washer most of the magnetic field will be going through the washer so it will be almost no risk to credit cards unlike a loose magnet.

Peter

[Bob C]

I'm glad to see the warnings about credit cards and hotel keys. I've messed up hotel keys with the magnet from a name badge a couple times at conferences.

The danger is real. I'd never use magnets in a sporran.

[Big Paul]

My Buzz Kidder has a magnet clasp. I haven't had any problems..