Uses a caddy
AppleCD 300 CD-ROM Drive is an internal drive using a SCSI interface. May also be called 300i or 300 Plus. These early drives use a caddy or cd carrier inserted into the drive. Models in stock are not Apple branded and are Sony drives, Model CDU561-25.
The drive pictured would be suitable for installation in an external housing or original application. Also available are modified drives that have had the volume button and headphone jack removed for probable installation in Macs or cases intended to have a tray load. All are tested to read CD's.