Hamilton caliber H-21 [Date]

The Hamilton H-21 is based on the Valjoux 7750. The H-31 is similar though based on the 7753. These movements most notable change compared to the standard version is the 60 hour power reserve. The following elements have been modified: - The entire kinematic chain has been refined, from the barrel to the escapement - The escapement regulator has been suppressed, facilitating optimal reliability and precision - The main spring has been improved to increase a typical power reserve of 60 hours.