It’s a case for SD cards, looking like an SD card. It fits up to 12 SD cards and 12 microSD cards. There is not much more to say.
Materials you’ll need
4 Pcs. 8x3mm Neodymium Magnet
Nope, magnets won’t ruin your SD cards
“Most modern storage devices like SD cards, thumb drives and SSDs are essentially immune to magnetic fields. In fact, there’s nothing magnetic in flash memory, so for all intents and purposes, a magnet won’t affect it at all.”