At Baselworld this year, Ball Watch Co. announced the Ball Engineer II Magneto S, a new mechanical watch with a patented magnetic protection system. Ball’s new technology, known as the A-Proof device, shields the movement from magnetic fields up to 80,000 Amperes per meter (A/m).
Magnetic fields are a real danger to mechanical watch movements. The effects of even a relatively slight magnetic force can throw off the timekeeping of a balance. When a movement has gone through a magnetic field, it may start to “gallop,” changing almost overnight from even timekeeping to excessive speed. To that end, watchmakers have employed various technologies to protect movements. Usually, for a watch to be considered “anti-magnetic,” it must be able to withstand a 4,800-A/m magnetic field and gain or lose no more than 30 seconds per day. The usual method of protection – and one that Ball Watch has used in the past – is to shield the movement in a soft iron cage. This protects the watch up to 12,000 A/m.
The Ball Engineer II Magneto S rethinks the materials used to guard against magnetism. Inside the Magneto’s stainless-steel case, the movement is surrounded by a shield made of “mumetal”: an alloy of nickel, copper, iron, and molybdenum. Known as the A-Proof device, this substance shields the watch up to 80,000 A/m. Ball Watch calls this “a completely new approach to the protection of a mechanical movement.”
Although A/m measure a different magnetic field than Gauss do, the 80,000 A/m that the Magneto can sustain is roughly equivalent to the 1,000 Gauss that the Rolex Milgauss is known to protect against.
Additionally, Ball’s Magneto includes an exhibition caseback, which has not been possible in traditionally protected anti-magnetic watches. A “diaphragm mechanism” underneath the sapphire crystal caseback can be irised open or shut by rotating the bezel. When it’s open, you can see the movement, and when its mumetal plates are closed, the caliber is entirely protected.
The Engineer II Magneto S has an automatic RR1103-CSL movement. It is COSC-certified as a chronometer. To protect it against shocks up to 5,000 Gs, it also uses Ball’s patented SpringLOCK system. It is water resistant to 100 meters. For timing, it has a standard three hands and a date window at 3 o’clock. The stainless-steel case is 42 mm in diameter, and has a screw-down crown. The watch comes on a black cordura strap. The price in Swiss francs is 2,900.