This is something for people that work on PCs. Not something you need very often, but very convenient to have around.
It's a device that allows you to use any internal hard drive as a USB drive without the need for an external enclosure.
Newegg link, model BT-300
I've been using one to transfer files to a new system drive and have had no problems. Just be sure to press the connector all the way in (see Newegg reviews).
Note: there is a model BT-200 that is $8 cheaper, but it does not do SATA.

