OMEGA. Men's chronometer wristwatch model "Seamaster Speed Sonic/F 300hz", steel barrel-shaped case with screwed caseback, metallic blue dial with baton hour markers and dots, three navy blue counters: double date and day windows at 3 o'clock, totalizer at 6 o'clock, minutes at 9 o'clock and seconds at 12 o'clock, black reptile-style leather strap and pin buckle (wear and tear and shocks on the glass). Quartz movement (revision and battery change required). 1970s. Diameter: 4.3 cm