The Cartier Ballon Blue line was introduced in 2007. It features a smooth, pebble-like case. One of its signature elements is the recessed & protected crown and the 'dent' it causes in the dial. Reference W2BB0022 has a stainless steel case with a yellow gold crown and a silver dial. It is powered by the self-winding caliber 049 and fitted with a stainless steel / yellow gold bracelet.