I thought an "ultrabay" was only for a hard drive

[angelofthesouth]

When I bought a used ThinkPad but discovered its hard drive bay was dead, I was pleased to find out that ThinkPads offered a hard drive bay that fits in the optical drive bay. A perfect solution to my problem.

I thought the device was called an "Ultrabay." In that case, why do I see the word "Ultrabay" on many (perhaps all) of the many used Thinkpad optical drives I have lying around? They are just normal CD/CD-RW/DVD drives.

[TPFanatic]

Ultrabay is the bay, the HDD caddies and various CD/DVD/Bluray drives are Ultrabay Devices. In older times Ultrabay Devices included batteries, a Serial+Parallel port adapter, or a slide-out numpad, however the last Ultrabay doesn't support these.