Keysight Technologies P939 A Series User Manual page 7

Only Keysight approved accessories shall be used.
To get the most out of your purchase, it is recommended that this User's
Guide be read carefully and completely.
This product has been designed and tested in accordance with
accepted industry standards and has been supplied in a safe condition.
The documentation contains information and warnings that must be
followed by the user to ensure safe operation and to maintain the
product in a safe condition.
Keysight P939xA Streamline Customs User's Guide 7