Lenovo - G550 2958 NoteBook PC, User Manual, Page: 100 / 128

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Appendix D. Customer replaceable units (CRUs)
Customer Replaceable Units (CRUs) are computer parts that can be
upgraded or replaced by the customer. There are two types of CRUs:
internal and external . External CRUs are easy to install, whereas internal
CRUs require some technical skills and in some cases might require tools
such as a screwdriver. However, both internal and external CRUs are safe
for removal by the customer.
Customers are responsible for replacing all external CRUs. Internal CRUs
can be removed and installed by customers or by a Lenovo service
technician during the warranty period.
Your computer contains the following types of external CRUs:
• External CRUs (pluggable): These CRUs unplug from the computer.
Examples of these types of CRUs include the AC adapter and power
cord.
• External CRUs with latches: These CRUs include a latch to help you
remove and replace the part. Examples of these types of CRUs include
the notebook main battery, an optical drive, a hard-disk drive, and an
extended battery.