1967 Seiko 300m diver 6215-7000

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Long before modern "Marinemasters," the 6215-7000 was Seiko's very first professional 300-meter diver. This 1967 monobloc-cased beast was a revolutionary engineering statement, featuring a crown uniquely positioned at 4 o'clock for ergonomics and a high-beat automatic movement. It is the raw, unadulterated blueprint that defined Japanese professional diving for the next half-century—an exceedingly rare, museum-grade grail.