Inside backcase : stainless steel 18 M0 watchstrap is not original
Similarities between the early Sea King line, shape of case similar to the SK "M" and has "waterproof" on the dial, handwinding. But also similar to the Surf King line, same jewel count, manual wind, sub-seconds dial.
Could be a "mix'n'match", but it's all original looking to me.
"Unknown", especially annoying since there are so many 1950's and 1960's ads around.
In reply to Case was used with the… by mybulova_admin
Found a close match in the 1964 Intl Line book BAWD0153. Slightly different hands and I believe the Waterproof was added later but l think the case and dial are a perfect match. Four year spread in add vs subject watch could explain the hand change. This confirms an international model and model number 511115 seems like a good ID.

