Ball Engineer II Magneto S Watch

Pretty interesting watch, especially the pinwheel caseback (in below link). Wonder how this compares to Milgauss?

I love Balls! Sadly I only have 1.

Hmm. That’s interesting. I haven’t seen this spin before. I am not sure if the iris mechanism justifies the resulting bulky case design. Also, why have a transparent case back for such a plain looking movement?