Page 187 of Manfred Rossler's "Zenith Swiss Watch Manufacture Since 1865" book says the following:
"Rectangular men's wrist watch, about 1976, steel case, reference 01.0040.380, automatic, date, Calibre 2572 PC, lacquered face. (Zenith collection)" although the picture shows it on a leather strap rather than the bracelet. Hope this helps.