Apple PowerBook (3400 series) - Manual (Page 165)

11 Gently touch the metal surface on the right side of the inside of the computer to
discharge any static electricity built up on your body.
This prevents you from damaging your Macintosh PowerBook or RAM card.
Don’t walk around while installing the card. If you do, make sure you do this
step again to discharge any static electricity.
Avoid touching the heat sink inside the computer
(shown in color here). If the computer has been
on for a while, or the power adapter has been
plugged in and charging the battery, the heat
sink may have become hot. You may wish
to allow it to cool for a few minutes
before proceeding with the
RAM card installation
procedure.
Touch the inside of the computer in this area to dissipate
any static electricity that may have built up on your body.
165 Installing a Macintosh PowerBook RAM Expansion Card