1940s round stainless steel vintage Zenith watch

A round stainless steel vintage Zenith watch. The case measures 31mm in diameter, with a screw back. The case is signed Zenith, Acier Inoxydable and numbered 8521020 to the back. The jewelled movement is signed Zenith and numbered 3699789, with a protective dust cover. The black dial has luminous Arabic numerals to the quarters, with hour indicators between and a subsidiary seconds dial. The dial is signed Zenith above the centre.