Cartier Ballon Bleu de Cartier Automatic 40mm（ WSBB0039）/WHP037150

"40MM White Dial
Stainless Steel Automatic Mechanical" 

Iconic blue balloon design: 40mm stainless steel case with a recessed crown (set with a blue synthetic corundum), continuing Cartier's "balloon" family's round and elegant style; silver guilloche dial (with radiating brushed finish) paired with oversized Roman numeral hour markers and blue steel sword-shaped hands, with a 3 o'clock calendar window that is practical and balanced visually.
In-house movement and performance: Equipped with Cartier's 1847 MC automatic winding movement (23 gem bearings, oscillation frequency 28,800 times per hour), with a power reserve of 42 hours, stable and precise timekeeping; 30 meters of water resistance meets daily protection needs, with a sapphire glass case back for scratch resistance and durability.
Wearing flexibility: Comes with a replaceable black grain-faced crocodile leather strap (with a stainless steel folding clasp), or an additional purchase of a stainless steel chain strap, allowing for a quick switch between "business formal wear" and "casual style".
Comfort and recognizability: 12.4mm thin case + arched crystal lens fits the wrist, the blue steel hands and blue synthetic corundum crown form the brand's iconic visual symbol, making it one of the most recognizable luxury watches in the world.