Hamilton caliber H-31

The Hamilton H-31 is based on the Valjoux 7753. The H-21 is similar though based on the 7750. 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. - The mono-block rotor is distinctively skeletonized with an “H” shape and aviation-inspired cut-outs, a signature of individualization.