Apple PowerBook G3 - Manual (Page 18)

Inserting an expansion bay module
To reinsert the expansion bay module, slide the module in. Make sure the
gripping surface is facing down. The release button automatically returns to
the locked position.
Be sure the module is completely inserted. If it does not insert properly, reset
the module release latch to the unlocked position (as in step 3 earlier) before
reinserting the module.
The expansion bay can use a wide component, such as the 5.25-inch CD-ROM
drive, or a narrower component, such as the 3.5-inch floppy disk drive. When
a narrower device is in the expansion bay, a small flap covers the empty part of
the bay. When a wider drive is inserted, the flap folds into the bay.
Note: A plastic storage case for PC Cards is provided with your PowerBook.
This case fits into the expansion bay. If you want to make the computer as
light as possible, you can remove the module in the expansion bay and insert
the PC Card storage case. Always keep a module or the PC Card storage case
in the expansion bay to protect the connectors inside the bay.
Flap for narrow module
18 Chapter 2