Very thin Swiss platinum keyless dress pocket watch Circa 1938

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A fine Swiss, very thin, platinum, keyless, dress pocket watch, circa 1938. A solid, polished, snap-on case back. Satine silver dial with painted Arabic quarter-hour numerals and baton indexes, outer minute track. Blued steel baton hands.  A rhodium-plated movement, Geneva striping decoration, 18 jewels, straight-line lever escapement, cut bimetallic compensation balance adjusted to heat, cold, isochronism and five positions, blued steel flat balance spring, index regulator. Dial, case and movement signed.
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Thickness: 4 mm
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Diameter: 45 mm
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Signed: Patek Philippe & Cie  Genève
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The dial is oxidized.