A mechanical movement has three enemies: moisture, dust and shocks. The first two have hardly been an issue since the introduction of water-resistant and water-proof cases starting in the 1930's, and systems like Incabloc and the more recent Nivachoc have made movements much more shock-resistant. Many watchmakers however add a fourth category to this list: magnetic fields. While magnetized movements were previously a problem of professionals who encounter high magnetic fields on the job -like doctors, railroad personnel and engineers-, with our ever increasing exposure to electronic devices, magnetism has become a very real danger for others as well.
The traditional solution to this problem is to encapsulate the movement in a Faraday's cage, as Omega did with the 1957 Railmaster, which was resistant to more than 900 gauss and developed especially for railway staff. For the Omega Seamaster Aqua Terra 15'000 Gauss however, Omega decided to spice things up and do it differently. This time the movement is not protected by an extra shield, but it is rather the movement itself which is made invulnerable to magnetic fields. Omega achieved this through the use of selected non-ferrous materials, which resulted in a resistance to magnetic fields of over 15'000 Gauss! In the words of the manufacturer:
'Even after exposure to a magnetic field greater than 15’000 gauss, the movement still performs at a chronometric level as defined by COSC.'
Since the movement is not protected by an additional container, it can be admired in full view through a see-through caseback.
Seamaster ref: 126.96.36.199.01.002