From my mountain of ancient machines, this was the original Apple CD transport... I used it with an SE/30 when I building BEHEMOTH in the Bikelab at Sun Microsystems. It has been sitting on a shelf in my lab ever since (non-smoking) and was powered up today as a test. It mounts and dismounts the carrier with a smooth whirring sound, but I have not tested with a computer (those SCSI cables are long-buried, not to mention not having a compatible Mac!)
From Wikipedia:
The AppleCD SC was the first CD-ROM by Apple Computer Company, introduced in 1988. It originally contained a fan but in 1990 they removed it because it was unneeded and attracted dust onto the optical disk head which could cause problems. It uses a front-loading caddy 1x CD-ROM and is only capable of Read Only Media. This accessory device was only able to read compact discs up to a 650 MB capacity in five formats, CD-Audio, CD-ROM, HFS, ProDOS, and High Sierra. On the front of the device it has an eject button, mini-phono sound out jack, and a volume knob. On the rear it has a power switch, power input, two Centronics 50-pin SCSI outputs, and an audio RCA connector. With appropriate software it would run on any Macintosh with a DB-25 connector, or an Apple II with an Apple II SCSI interface card.Weight is about 11 pounds boxed, and this includes the two CD caddies shown in the photo. Original power cord long gone, but generic used black one is included.
From reading about these, common advice is that they should be recapped. I have not looked inside, but given the age that sounds like a wise idea.