Apple Power Macintosh 4400 - Manual (Page 157)

5 Check the external connector on your card, see which of the following two illustrations
matches the card you have, and install the card according to the illustration.
If the card has a hook, make sure it engages the hole in the access cover
before you push the card into the slot.
Communication card slot
Communication card
Communication card
access cover
If your communication card
has a hook on it (as shown here),
be sure that the hook engages
the hole in the access cover.
157 Installing Expansion Cards and Additional Memory