Designed by Gérald Genta, the Royal Oak watch was the first luxury sports watch housed in an imposing stainless steel case, which cost more than the gold model. Touted as having "a body of steel and a heart of gold" the stainless steel armour of the Audemars Piguet Royal Oak watch, with its eight-sided bezel and exposed screws, had an industrial edge to it, while the "heart" in the equation referred to Calibre 2121 - an ultra-thin 3.05mm automatic movement with a gold oscillating weight.