A CRU (customer replaceable unit) is identified by a single asterisk (*) or two asterisks (**) in the CRU ID
column. An N in the CRU ID column means that the part is not a CRU. A single asterisk (*) means that the
part is a Self-service CRU; two asterisks (**) means that the part is an Optional-service CRU.ThinkPad
Notebooks contain the following types of CRUs:
Self-service CRUs
These CRUs unplug or are held by no more than
two screws. Examples of these types of CRUs
include an ac adapter, a power cord, a battery,
and a hard disk drive. Other Self-service CRUs
depending on product design may include a
memory, a wireless card, a keyboard, and a palm
rest with finger print reader and touchpad.
Optional-service CRUs
These CRUs are isolated parts within the computer
that are concealed by an access panel that is
typically secured by more than two screws. Once
the access panel is removed, the specific CRU is
visible.