Fifty is a big milestone. It’s been that many years since Audemars Piguet introduced the Audemars Piguet Royal Oak in 1972 and unleashed a new concept of wristwatch on the world: that of the lifestyle-oriented luxury sport watch. Today, the watch and the genre it created are hotter than ever, and to celebrate its birthday the brand is announcing the next generation of Royal Oak — but how do you reinvent an icon?

Although Audmars Piguet isn’t known to be totally risk averse, it would be folly to mess too much with a good thing. The brand needed to respect Gerald Genta’s original design, but a major anniversary offers a chance for a refresh and to integrate tweaks and upgrades. This is exactly what they’ve done, and although at first glance it feels like a familiar Royal Oak, the differences are indeed many. Here’s what you need to know: The core collection is getting new 37mm Selfwinding models, as well as 38mm and 41mm chronographs. They’re going to be slimmer with a range of elements to improve ergonomics — the Royal Oak already known to be an exceptionally comfortable watch. Thanks to a new movement (see below) and other elements such as a caseback redesign, it’ll now sit even better on the wrist. As previously introduced on some precious metal watches, the famous steel bracelet is now even thinner (and therefore lighter).

The Audemars Piguet Royal Oak Chronograph. This is a watch that is so known to many of you, it may not need much of an analysis – but this is HODINKEE and you can believe you’re gonna get one. The Royal Oak Chronograph is a watch that has thousands of lovers the world over, and a few detractors, too.  The ROC, as I’ll call it henceforth, is something of a middle ground between two completely distinct Audemars Piguet buyers – the collectors, and, well, everyone else. The Royal Oak and Royal Oak Offshore families often appeal to very different people, but I’ll get to that shortly. In this review, I tackle a mainstay in the AP lineup, and an interesting piece of haute horology, though one without its own in-house movement. I will look at how this 41mm column-wheel, vertical clutch chronograph wears, and if the matter of where the movement came from is even something worth noting at all. This is your HODINKEE Week On The Wrist with the Audemars Piguet Royal Oak Chronograph, and it’s one worth spending some time with.

Just as Mark teased in his introduction for the 39mm blue dial 26670 back in April, the new 26660ST wraps that metallic purple dial in a 37mm steel case. Maintaining the same 8.1mm thickness of the 39mm RD#3, the new 37mm model is also water resistant to 50 meters and has a steel bracelet with the usual AP folding clasp.

The movement, too, is the same found in this year’s earlier release, AP’s ridiculously-thin (just 3.4mm) automatic caliber 2968, which ticks at 3 Hz and offers a 50-hour power reserve with which you can watch the lovely titanium flying tourbillon, set flush at six on the dial.