Check out the ultra-thin Royal Oak watch Audemars Piguet just unveiled to mark the 50th anniversary of the watchmaker's most popular line

• Swiss luxury watchmaker Audemars Piguet has been making its popular Royal Oak timepiece since 1972.
• The company just unveiled a 50th anniversary model: the Royal Oak Selfwinding Flying Tourbillon Extra-Thin.

One of the most coveted watches in the world just got a new look.

Swiss luxury watch manufacturer Audemars Piguet just unveiled a new model of its popular collectible watch, the Royal Oak. Dubbed the 39-mm Royal Oak Selfwinding Flying Tourbillon Extra-Thin, the model commemorates the 50th anniversary of when Audemars Piguet started making the Royal Oak back in 1972.

"The Royal Oak continues to evolve and cut through the timeline 50 years after its creation and will do so for the next 50 years and beyond," said Michael Friedman, Head of Complications at Audemars Piguet, in a press release.

While the anniversary model's price is not listed, Royal Oak watches typically sell for between $13,407 and $370,001 on the private sales market, according to industry price-tracker WatchCharts. Some watches in the collection have fetched more than half a million dollars in the past.

The watch's self-winding flying tourbillon was previously reserved for bigger, 41-mm models, and Audemars Piguet says fitting it into this smaller model is a first for the company and a rare instance in the industry as a whole.

"It remains a platform for both technical and aesthetic development, as demonstrated by the new ultra-thin flying tourbillon making its debut on both the classic 39 mm and the celebrated 37 mm Royal Oak models," said Friedman in the press release.

The stainless steel watch also features a sapphire caseback, a blue dial with the signature Petite Tapisserie pattern, white gold applied hour-markers, and luminescent coating on the hands for readability at night.

"The movement architecture was designed to offer a unique view of the smaller cage while showcasing an engaging contrast of hand-finishing techniques throughout," Friedman added in the press release.