Quote Originally Posted by rfrazier
Or, perhaps standard steel bonded to something like mu metal?
The 656 caseback is not a composite material ... Mr. Schmidt said that they managed to make the shielding material the same look and hardness as the rest of the case (316L material).

Apparently a major hurdle in the production of antimagnetic watches is the dial, by the way (the movement ring is not a great challenge, by comparison). The dial-makers need massive help from Sinn to put the dial print onto the antimagnetic dials which obviously have different properties from brass (or whatever material is used) dials..