First up is my favourite watch. My Boucheron La Carree Ultra Thin which is 25mm x 25mm and is just 3.3mm thin Circa 1960.

Boucheron La Carree Ultra Thin 1

Boucheron La Carree Ultra Thin 2

Boucheron La Carree Ultra Thin 3

Boucheron La Carree Ultra Thin 4

Boucheron La Carree Ultra Thin 5
Then we have my Breguet Classique 3150BA/11/286 which is 33mm and 4.3mm thin Circa 1986.

Breguet Classique Ultra Thin

Breguet Classique Ultra Thin side view

Breguet Classique Ultra Thin in Breguet box
Lastly a picture comparing the two watches.

Boucheron La Carree Ultra Plate & Breguet Classique Ultra Thin
Sorry no wrist shot of the Breguet as still awaiting my made to order strap for it.
Marc