Swiss stainless steel pocket tachymeter chronograph Circa 1935

Pocket chronograph with 5-colour-multiscale dial by Omega
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A rare Swiss Omega pocket watch chronograph, Chrono-Tachymeter, Cadran Brevetè SGDG, with a 5-coloured tachymeter scale and register, circa 1935.
Rare polished stainless steel case, case number 8214679, factory number 7685629, calibre 39CHRCO, so-called Chrono–Tachymeter. Special enamel dial SGDG Tachyzifferblatt with 5-coloured tachymeter scale, subsidiary dial for the seconds, subsidiary dial for the register, centre chronograph hand, and Breguet-style steel hands.
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Diameter: 50 mm
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Weight: 135 g
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Signed: Omega Cadran Breveté S.G.D.G
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SGDG tachy dial: It enabled direct reading without calculating all speeds between 10.5 and 240 miles per hour. The 30-minute counter begins with five different-coloured minute segments to indicate which colour of the spiral-shaped tachometer scale the speed can be read from.