Sony PCG-XG28 Primary User Manual page 115

You can increase your system's memory by installing optional memory
modules. Your system comes with 128 MB of installed memory, which
can be increased up to 256 MB (128 MB x 2). You can add an expansion
memory module in a slot. Up to 128 MB expansion memory modules are
available as optional memory modules.
Electrostatic discharge (ESD) can damage disk drives and other
components. Perform the procedures described below only at an ESD
workstation. If such a station is not available, do not work in a
carpeted area, and do not handle materials that produce or hold static
electricity (cellophane wrappers, for example).
Ground yourself by maintaining contact with an unpainted metal
portion of the chassis while performing the procedure.
Do not open the memory module package until you are ready to
install the module. The package protects the module from ESD.
Use the special bag for preventing ESD or use aluminum foil when
you store the memory module.