This is a handsome 1960s Oriosa chronograph, originally rated to 20 ATM (200 metres/660 feet). It has just been professionally serviced and is fully functional, keeping time to approx. +/-10 seconds in 24 hours and running for 43 hours on a full wind.
Dimensions approximately 37 mm without crown.
The watch has a manual-wind Landeron 248 movement with Incabloc shock-protection.