Back when CompactFlash was the mediums of choice, you could get it in two formats, flash obviously, & Microdrives
Same concept used in the iPod, same technology used in the iPod Mini, it is a hard drive in a compact formfactor
All of mine have outlasted all of my flash cards...
I’ve got one even older; this 8.7 GB 2.5” IDE SSD from 2004. I still use this in an old laptop running Windows 98, and it still works great today!