Invention of the Ball Bearing Rotor In 1948, Eterna announced a friction-reducing ball-bearing mounted rotor system as part of the...
Ball Bearing Rotor
Manufacturer ETA / Valjoux Caliber Number 7753 Movement Type Automatic Jewels 27 Power Reserve 48 hours Diameter 13 1/4”’ (30.00mm)...
Manufacturer Montblanc Caliber Number 4810 503 Base Caliber ETA / Valjoux 7753 Movement Type Automatic Jewels 27 Power Reserve 48...
