C&K systems System 238 User Manual page 22

DURESS ALARM
(238i and 2316i ONLY)
OPTION
INSTALLED
Should an intruder force you to turn your security system off or on, you can
send a silent DURESS signal to our central station by entering User Code 7 -
a code designed exclusively for a DURESS signal. Your system will appear to
be operating normally. There is no indication of an alarm condition.
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