Instant Pot DUO NOVA Series User Manual page 26

Pressure Control Features
Condensation Collector
The Condensation Collector holds the condensate that collects naturally in
the Condensation Rim while cooking.
To install the Condensation Collector, align and slide the grooves on either
side of the top of the reservoir over the tabs in the reservoir holder at the
back of the cooker.
Do not operate the pressure cooker without the Condensation
Collector installed.
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