I got one of these to extract some data off an old laptop hard drive (at the time those data transfer cables were not available). It comes with a sleeve and a small screwdriver to remove the end casing. The drive just plugs into the connector inside, the end casing goes back on, replace the two screws and it's job done! Just plug it in with the included USB lead and the drive will appear as an external device. The lead has two plugs on one end, this is to provide extra power to the drive if needed, however I never needed to connect this second plug. The drive is powered off the host machine so does not need an external supply unlike a 3.5" external enclosure.
The case I received was blue instead of silver like the image, but that did not matter to me. It still looked good! :-) It also has a red LED on the USB connector end to show data transfer activity.