Audemars Piguet has soared to astronomical levels of fame over the past decade through the proliferation of the Royal Oak, its presence in modern pop culture, and the subsequent hype that followed. Despite the meteoric rise in popularity that has made Audemars Piguet a recognizable name in households around the planet, the Le Brassus-based haute horlogerie manufacture has kept its sights set on the metaphorical horizon with incremental improvements throughout its lineup, as well as monumental advances in complications and materials. The new Royal Oak Self-Winding Perpetual Calendar Ultra-Thin — casually and affectionately known as the RD #2 — falls in the former category of strategic incremental improvements that edge closer to perfection.

Some of the most impressive and complicated watches to come out of the Le Brassus manufacture receive the special designation of “RD,” meaning they come from the research and development segment of Audemars Piguet with a unique goal in mind. In the case of the RD#2, it claimed the title of “World’s Thinnest Automatic Perpetual Calendar” upon its launch in 2018. While it can’t claim this anymore, there is no disregarding that a 6.2mm thickness is still absolutely wild for a mechanical wristwatch, let alone a self-winding perpetual calendar of this caliber (pun intended).

That 6.2mm-thick measurement is the fully encased and ready-to-wear watch. Crafted in titanium, the 41mm-wide RD#2 exemplifies the high standard of finishing that Audemars Piguet has for its watches, and the dazzling results it produces compared to some other recent titanium releases. Housed inside is the Calibre 5133 — the same movement as the previous RD#2 variants — which clocks in at only 2.89mm-thick. David Bredan broke down the ingenious movement and its intelligent display in his hands-on review, and I highly recommend reading it for a thorough understanding of the caliber 5133’s mechanical prowess.

This ultra-thin perpetual calendar movement displays the day, date, month, and moonphases, tracks the leap year, provides a day/night indicator, and, of course, hours and minutes. You can observe the movement comprised of 256 parts beating away at 2.75Hz (19,800 VPH) through the sapphire caseback. This uncommon frequency yields a 40-hour power reserve, which, by normal standards is disappointing but is understandable for a perpetual calendar. I would have liked to see improvement here by the third iteration.

You may be asking yourself, “If this is the same watch, with the same movement and case as the previous versions, then what is actually new about it?” The preceding watches had a mix of finishes, materials, and dial options that, when combined, give you the close-to-perfect ultra-thin QP, which we have here. The most obvious update is the dial. Beneath the flat sapphire crystal is a smoky blue-to-black gradient with a sunburst finish. It lacks the tapisserie dial the Royal Oak is known for, which can be found on the first-generation RD#2, but makes up for the somewhat flat appearance of the vertically brushed second-generation dial. The addition of snailed (concentric circle) black subdials provides immediate contrast, improving legibility while also giving the ultra-thin watch a sporty appearance. A full titanium case and bracelet construction with brushed surfaces and polished bevels, instead of the mixed metal and polished scratch-magnet bezel of the previous generations, rounds out the shift to a more athletic-designed sports watch. Despite this shift, the RD2 retains its 20m water-resistance rating.

The previous generations of the RD#2 paved the way for the penultimate “blue panda” Royal Oak calendar sports watch. Audemars Piguet worked the kinks out by trying precious metals and different dial designs, but something never felt quite right — until now. With a perfectly balanced dial, ideal case material, functional finishing, and an effortlessly elegant movement, the newest Audemars Piguet Royal Oak Self-Winding Perpetual Calendar Ultra-Thin checks all the boxes of the horological endgame, even the limited-edition box. The new RD#2 is limited to 200 pieces at a price of CHF 137,000. Learn more about the Audemars Piguet Royal Oak Selfwinding Perpetual Calendar Ultra-Thin on the brand’s website.