Omega Seamaster 600 135.011 manual wind watch

A really fine black-dialed Omega Seamaster 600 manual wind watch. The dial has some minor pinpoint patina, visible when viewed against the light. The case shows signs of age and use, and there is an engraving on the case back. The crown is original, and the leather strap is used. Service history is unknown, but the watch functions well, with a deviation of about 10 seconds per day.