Seiko Spring Drive Tuna Montone meaning a very thin case

meaning a very thin case profile that is easy and comfortable to wear under the cuff

there is an enthusiastic group of collectors who seek these rare references

It features a 39mm PVD case with a mineral crystal

with a red triangle in the 30 minute subdial for timing regattas

Seiko Spring Drive Tuna Montone meaning a very thin caseIt started with a letter. In 1968, a disgruntled professional diver in Hiroshima wrote to Seiko to complain that the dive watch he had been using simply was not robust enough. When exposed to prolonged pressure at depth, the watch filled with helium, he wrote. The crystal would pop off, rendering a vital piece of equipment useless. Seven years and 20 patents later, the first Seiko Tuna emerged The first Tuna, Reference 6159 7010, was released in 1975