Zenith EL PRIMERO 21 9004 Mode D'emploi page 17

PLEASE be aware that Zenith's international warranty does not
cover normal ageing of your watch, natural wear and tear of the
leather, fabric or rubber straps, nor any scratches that may appear
on the case or sapphire crystals during use.
Your watch and its movement deserve a special kind of care:
In order to maintain their accuracy, Zenith service centres
recommend servicing your watch every 5 years.
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