Cartier launched the Ballon Blue collection back in 2007, showcasing a sleek and round case design. A standout feature is the recessed crown, creating a unique "dent" in the dial. The Extra Flat models in 46mm and 40mm were added in 2011 and 2015 respectively. The W6920054 model stands out with its 46mm pink gold case and hand-wound caliber 430 MC. The dial is a stunning silver color.