Happily wearing this after a successful de-magnetization. I have a 1861 Speedmaster which I suspected was magnetized after its timekeeping jumped one day from -4s/d to +16s/d; now de-magnetized, it's back to -4s/d. The Geophysic had been running at +18s/d since I purchased it, which I attributed to lack of service. When I checked the Geophysic on the 'is it magnetized?' app on my phone, it indicated: Magnetized. A couple of trips through the de-magnetizer and Voila! It's now running at +2s/d 😀