I finally caught the elusive Scubapro 500 dive watch with "tuna can" case. The watch looks similar to the Seiko 6159 7010 600m tuna but the main difference is the case of the Scubapro is stainless steel and that of Seiko is titanium. The shroud of both watches are made of titanium but the Scubapro is PVD coated and the Seiko is ceramic coated. Scubapro is a well known American dive company that supply top of the line dive gears The company became famous when their silicone dive mask was used by Jaqueline Bisset in the 1977 movie "The Deep". My quad Tuna collection: