Basically it was like one of those faux floppy disks that accept mini-SD cards and require special drivers ... except this one worked in DOS, and in fact contained a generic 720KB floppy drive compatible boot track and a few sectors (enough for a DOS boot apparently), so basically you could stick it in any IBM Compatible that boots 3.5" and it would boot the DOS sector, load some driver, and redirect the boot process to the mini-SD setup now known as drive C:. So essentially you "insert a hard drive" into any darn thing, which would be nice for some ancient laptops that never knew the pleasure of an HDD...