If you think making an automatic grand complication watch in a super low profile case is difficult, you’re right. But AP did it. The world’s thinnest automatic perpetual calendar watch, the Audemars Piguet Royal Oak Perpetual Calendar Ultra-Thin has a height of 6.3mm, a full 3.22 thinner than the standard Royal Oak Perpetual Calendar. The Caliber 5133 movement itself is only 2.89mm thick.

With a 41mm satin-brushed titanium case and integrated bracelet, this handsomely crafted timepiece features a vertically brushed matte blue dial, blue-on-blue subdials, and polished white gold markers. The Royal Oak Perpetual Calendar Ultra-Thin is priced on request.