CERTINA, Chronolympic, "Tachymetre, Base, Pulsations", chronograph, wristwatch, 43 mm,

The Chronolympic models were Certina’s best-known and most successful line of chronographs, and featured a lot of interesting and beautiful pieces. The first Chronolympic models (Ref. 8501 503) came to the market at a time when chronographs were becoming popular again at the end of the 1960s. Manual winding movements like the Valjoux 232, 234 and 726 were initially used, before an automatic version with the Valjoux 7750 (Ref. 674 3559 41) was launched in 1975.
(Source Vintagecertnas.ch)