The Apple PowerCD was introduced in 1993 by the Apple's Mac Like Things group. It could act as a stand alone music CD player, a SCSI CD-ROM drive, or a Kodak PhotoCD drive. PhotoCD's never caught on, but with the PowerCD's portability and battery power it became popular as a CD-ROM drive for Powerbooks.
Like all of Apple's products of the time, the quality is superb. The drive has a very substantial feel (i.e. it's heavy) and the display is even backlit.