Grand Seiko 3180
The Grand Seiko caliber 3180, later renamed 5720, is a manual winding mechanical movement, introduced in 1960 with the Grand Seiko First model. It combined some characteristics of the movements previously developed by Seiko for the Lord Marvel and the Crown. The accuracy was +12/-3 seconds per day. Caliber 3180 (later renamed 5720) Type Mechanical Manual Family 57GS Year 1960 Jewels 25 Bph 18,000 Accuracy +12/-3 seconds per day Complications …