Low profile and medium protecting cartridge assembly

The present invention is directed generally to a low profile cartridge and specifically to a low profile cartridge for an optical disk. Various configurations of cartridges for optical disks, particularly first-surface optical disks, are provided. The cartridges include a plurality of protectors for use in safeguarding the optical disk when certain conditions are present or certain events occur. The protectors include an elongated shutter that covers the hub assembly, at least annular slot portions inside of the cartridge to restrain movement of the disk within the cartridge, a locking subassembly to hold the shutter in a desired position, and a mechanism for preventing complete insertion of the cartridge into an optical drive when the cartridge is in the wrong orientation relative to the drive.