The Seamaster 600 Professional model, also called "PLOPROF" for PLOngeur PROFessional, professional diver, was launched in 1970. It took over 4 years of study and research to design this watch. The monocoque case is made out of one piece of massive steel.
Commander Jacques Cousteau used a "PloProf" during a series of experiments at depths of around 500 metres.
The present watch with the winding crown to the right and the bezel lock/release button to the left side is the rarer left-handed version.
The "PloProf" is explained and illustrated in Omega Saga by Marco Richon, pp. 136/137.