Preventing magnetic fields from affecting the accuracy of a mechanical watch can be done in different ways. The most recent evolution of the early 2000s involves manufacturing a balance spring made of silicon. The old-fashioned way, made possible by transitioning to the thinner caliber M100, consists of building a soft-iron cage around the movement to redirect magnetic fields. This cage, composed of three parts, improves the current Swiss standard in magnetic resistance by 10 times, upgrading the usual 4 800 a/m to above 50 000 a/m. #serica #sericawatches #watchmaking #sportswatches #goingtheextramile #automaticwatches #refinedsimplicity #toughwithcharm #swissmade #5303 #serica5303 #COSC #5303cosc #chronometer #amagnetic #antimagnetic