The 6159-7001 was Seiko's third professional dive watch. It features an amazing monoblock case. The case, bezel, dial and hands are all in very good shape. While it is the third in Seiko's professional dive watch history, it's considered the first actual professional-grade dive watch, and a very important part of Seiko's dive watch history. It is the basis for a re-creation in the recently released SLA025 It has a 36000 bph hibeat movement, 6159. It was first produced in 1969. It is 44mm case, not including the crown. The watch works well, I do not know its service history. I'm asking $6500 US, OBRO. Payment wire transfer or Zelle.