Well thought through anti-magnetic timepieces
Most of the BALL watches boast superb anti-magnetic cases constructed with corrosion-resistant ferritic stainless steel materials. Furthermore, a soft iron inner jacket, consisting of a back plate, a ring surrounding the movement and the dial, protects the inner workings of the watch. This special alloy, reinforced by the shape of the case, prevents magnetic fields from penetrating as far as the movement and having an adverse effect on its accuracy.
The anti-magnetic standard
"What does the term «anti-magnetic» actually mean? The existing standard is defined thusly: An «anti-magnetic» mechanical watch does not stop when exposed to a magnetic field of 4,800 A/m and subsequently does not deviate by more than 30 seconds per day.
Anti-magnetic timepieces from BALL Watch certainly surpass this standard, particularly the Engineer Hydrocarbon series with 12,000 A/m standard protection."