We define a drive dock as a device that allows a quick change of a hard disk drive with the need for a caddy or a drive tray. The Serial ATA interface with it's slide on power and interface connectors, and the hot-swap ability have allowed this class of drive system to become available.
Care must be exercised not to attempt to swap out a drive that is in use, part of a RAID set or one that is being used as a boot volume.