1968 Zenith Chrono cal. 146DP ref. A278, 37mm. case.

The 146 is the last manual wind chronograph movement used prior to the introduction of the el Primero automatic.

Zenith is a luxury Swiss watch manufacture started in 1865 by Georges Favre-Jacot at the age of 22. Zenith was purchased by LVMH in November 1999, becoming one of several brands in their watch and jewellery division.
Zenith has a long reputation for the quality and precision of their watches. It is one of the few Swiss watch manufacturers that still produce their own movements in-house, including the Zenith el Primero one of the first automatic chronograph movements from 1969.