Jaeger-leCoultre REVERSO CLASSIC MEDIUM THIN Instructions For Use Manual page 26

once it has been assembled, in the condi-
tions closest to daily wear.
The "1000 Hours Control" legend, or the
" " seal engraved on the back of the
watch certifies that each of the models
from our collection has successfully under-
gone all of the qualification tests, and that
your watch has successfully undergone
all of the production tests. These ensure
regularity of rate, resistance to variations
in temperature and atmospheric pressure,
ability to withstand shocks and magnetic
fields, as well as water resistance.
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