iwc IW3903 Operating Instruction page 21

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I N F O R M A T I O N A B O U T M A G N E T I C F I E L D S
As a result of the ever greater prevalence in recent years of very strong magnets
made from rare­earth alloys (for example neodymium­iron­boron) – these are found
in objects such as loudspeakers, jewellery and fasteners on mobile­phone cases and
handbags – mechanical watches are increasingly likely to come into contact with
such mag nets and be magnetized. This can lead to the watch rate being permanently
affect ed, a problem that can only be resolved by a process of demagnetization car­
ried out by a specialist. We recommend that you keep your watch away from such
magnets.
Watches with a soft­iron inner case provide a higher level of protection against mag­
netic fields and far exceed the requirements of DIN standard 8309. Nevertheless, it is
still possible for the watch movement to be magnetized in the close proximity of very
strong magnets. We therefore recommend that watches with a soft­iron inner case
also be kept away from direct contact with strong magnets.
Should there be a sudden change in the precision of your timepiece, please contact
an authorized IWC Official Agent to have your watch checked for magnetism.
P O R T U G I E S E R C H R O N O G R A P H C L A S S I C