bora CKAS Notice De Montage Et D'utilisation page 32

Operation
GB
If the gas cooktop is operated with the hob extractor,
the cover plates must be placed. A distortion of the
flame is thus avoided.
If the hob extractor is operated with two gas cooktops
at the same time, a second cover plate set must be
installed so that flame distortion is avoided for both
gas cooktops (all four cooking zones).
Note:
Safe operation can only be ensured with
BORA–Classic–Cooktops.
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