Apparently the Kryoflux adapter will give you a floppy controller to USB. This means than since modern motherboards (eg Intel socket 1155) do not have floppy controller, or older (eg Intel socket 775) had but didn't support 5.25" drives or supported a single floppy, now we can actually have up to two floppy drives of any kind (PC or MAC or Amiga, Commodore etc). So, as far as I understood, with that adaptor you get the needed floppy controller, then you need an appropriate floppy cable to connect your 5.25" drive (thanks God, I have kept one or two, it's nearly impossible to find one today). Probably you will also have to connect the drive with power (mine takes the standard molex, so no problem, even for a modern power supply). Then if everything goes OK, the drive should appear as A: in My Computer, or at least you can access it using Kryoflux's software. As they claim, you can read and write to the drive, so not only you can backup all your old floppies, you can use them for (very small) file transfer. Unfortunatelly, a 5.25" PC disk is only 360KB (single sided, double density) or at most 1.2MB (single sided, high density) so there is no much use by todays standards. Needless to say that to access a 1.2MB disk you need a high density 5.25" drive, while a 360KB disk can be accessed by either a high density or double density 5.25" drive.
So I would look no further, I would go for the Kryoflux solution, if I had too many floppies to read. Another solution, is to use an older computer, if available, that can accept the old drive without any adaptors. Backup all your disks to another medium (CD, or USB etc) and then you shouldn't need the drive anymore, since the disk capacity is TOO small by today's standards and it is useless to use these disks for saving data. And since we are talking about a 5.25" drive, most data (and games, programs etc) in it must probably be from MS DOS era, so you can use them in DosBox emulator. It works perfectly, even in 64-bit Windows! There is even a way to install Windows 95 in a virtual disk, if it happens to have any old windows game you want to play in 64-bit Windows. Of course, the game must play in Windows 95, if you need newer Windows version, try Compatibility Mode on your host Windows system, or use a better virtual PC application such as VMWare.