Omega De Ville Prestige 40 mm, steel on steel – 434.10.40.20.

Diameter: 40.0 mm. For example, some refs list a 40.0 mm case for the De Ville Prestige 40 mm models.

Case material: Stainless steel. For the “steel on steel” designation you noted, this means steel case + steel bracelet.

Bracelet: Stainless steel bracelet (matching the case) in the “steel on steel” version.

Crystal: Domed sapphire crystal (with antireflection on some variants) is standard in recent Omega De Ville Prestige models.

Movement: Many of the newer De Ville Prestige 40 mm models are powered by the calibre 8800 (Omega’s Master Chronometer certified movement) in the “Co-Axial Master Chronometer” variants.

Water resistance: Low — typical listing shows around 30 m (3 ATM) for these models. For example: one listing: “Water Resistance: 30” for ref 434.13.40.20.06.001.

Dial & design: The dial tends to be relatively clean, elegant, classic dress-watch style (Roman numerals or indices, date window at 6 o’clock in some versions) for the Prestige line.