An object being non-magnetic means it does not attract ferrous metals and has no magnetic properties. In horology this means the watch is not affected by magnetic fields due to being constructed from non-magnetic materials or is protected from being so.
Special springs are used in these watches such as those by Nivaflex, Durober and Vimétal.
When non-magnetic materials are not used another method is to house the entire movement into a case made of a highly conductive (permeable) material.
This functions like a screen drawing lines of force to it, thus protecting the movement of the watch.
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