These were quite common around 1994-1996. There were quite a number of companies selling the cases and it was up to the buyer to source a suitable 2.5" SCSI drive. Often people would put an old PowerBook drive to good use after upgrading the PowerBook to a larger drive.
As register said, power was usually taken from ADB, but on some laptops, the ADB ports couldn't source enough current and an external regulated 5v power supply was needed (or a desktop Mac with an ADB port nearby if you were stuck!).
They were fantastic for quick on site fixes. You could boot any Mac from the drive, use a disk utility to check & fix the disk catalog and / or re-install the System very efficiently with one of those and the right software.
Unfortunately, out in user land they tended to live fairly short lives. Drop one and the drive mechanism is history.
As register said, power was usually taken from ADB, but on some laptops, the ADB ports couldn't source enough current and an external regulated 5v power supply was needed (or a desktop Mac with an ADB port nearby if you were stuck!).
They were fantastic for quick on site fixes. You could boot any Mac from the drive, use a disk utility to check & fix the disk catalog and / or re-install the System very efficiently with one of those and the right software.
Unfortunately, out in user land they tended to live fairly short lives. Drop one and the drive mechanism is history.