Sinn 556 A Cowhide Leather Watch SN-269

Sinn Instrument 556 A Cowhide Leather 556.014 Cowhide Leather. From the beginning, Sinn’s emphasis was on creating special purpose instrumental watches that performed under extremely adverse operating conditions such as high speed, high and low pressures and altitudes, intense heat or pressure, extreme cold, high magnetic interference, and submergence in liquids.