
Not only for SD cards! I've also used them as emergency holders for some loose safety pins. Can also be used for beads. But it works fine for my SD cards

JJC Camera SD TF Micro SD Memory Card Case Holder Organizer Box with Card Removal Tool & Lanyard - Water-Resistant Storage for 4 SD & 4 TF Cards
12 Review

High-Speed Transcend TS-RDF5K USB 3.1 Card Reader for SDHC/SDXC/microSDHC/SDXC Cards - Black
11 Review

IDENTIV USB Smartfold Type C SCR3500C
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π» LEEGLOAD 4 in 1 SD Card Reader Adapter for iPhone/iPad/Android/Computer and Digital Camera, Memory Card Adapter with USB C/USB A/Micro USB, Trail cam Card Viewer (Black)
13 Review