The Breitling Watch Source Forums

This ad is well circulated on forums and shows most of the the 17x series with measurements in lignes ('''). Does anyone know what the measurements are for? The diameter of the uncased dials?

Also, any idea what the phrase "extra plat" means (next to the ref. 176 and ref. 178)?

It's a ligne measurement for the movement - https://en.wikipedia.org/wiki/Ligne

Extra plat = extra flat in French, i.e. a thin watch.

Thanks! And that leads to my next dumb questions....

Don't the 17x's watches all have a Venus 170 movement? And if so, how could the movements in this series have different measurements?

not dumb at all.
as far as I know, all 17x had the Venus 170 - and that clearly is a 12.5 lignes movement, no larger versions exist afaik.

as the lignes info indicates movement siozes in the catalogs typically I would have automatically replied the same as Roff; but in this case the lignes numbers apparently indicate dial sizes as you thought.

Just measuring my stainless steel 178 ( NOS case ) , the thickness of the complete case - with caseback and crystal = 11.08mm . Diameter = 34.96mm . Dial aperture = 32.40mm .
I have compared with a NOS 734 case ,thickness 12.08mm dia 37.42mm , dial aperture 34.47mm

I've been after the ref 179 for a while since it appears to be a strangely larger case. Only seen one and it was in poor condition.