Medical Device?
Q: Does anyone know if a magnetic clasp would interfere with a computer, or a medical device?
A: This is just a guess, but I don't think a small magnet would be a problem. I once tried putting 30 half-inch diameter super-strong ceramic magnets on a floppy disk and left it for a week. Not one byte of the data was erased or corrupted. We used an electromagnet in journalism school to erase our radio tapes. It was huge, loud, and obscenely strong when turned on, but even then, you had to hold your tape on it and move it around for a good 10 seconds to completely erase it. You probably want to let possible buyers know that its there, but I think it would be fine for the most part if it's small. Yes, they'll wipe your credit cards. Also people who have internal medical devices (pacemakers, insulin pumps, etc.) and people who use transdermal patches (nicotine, BP, hormones, etc.) shouldn't use magnetic jewelry because it will change how the device/patch operates.