The Oris Big Crown ProPilot Altimeter is a wrist Cartier replica watches equipped with a mechanical barometric altimeter-and-barometer movement. In fact, it is the world’s first automatic mechanical altimeter watch at an affordable price. Learn more about it in this in-depth review, excerpted from my blog, Watch-Insider.com.

Here’s how Oris describes the new watch in its press release: “The Big Crown ProPilot Altimeter has been developed entirely by us to serve as a high-performance instrument for pilots, mountaineers, explorers and research scientists, who work at altitude. Its sturdy, 47-mm multi-piece stainless steel case houses an automatic movement, and a Swiss mechanical barometric altimeter and barometer movement.” The Oris Big Crown ProPilot Altimeter has two crowns. The one at 2 o’clock is a conventional crown to adjust the time and date, and to wind the watch as necessary (the automatic Sellita-movement has a 38-hour power reserve), while a second screw-down crown, at 4 o’clock, operates the altimeter.

When screwed down into “Position 0,” the altimeter is inactive and the fake Rolex watches is water-resistant to 100 meters; the altimeter is activated by unscrewing the crown into “Position 1,” which is indicated by a red ring. When the crown is pulled out into “Position 2,” the altimeter can be calibrated. Once set, the watch shows the current altitude via the yellow indicator, and the corresponding air pressure via the red indicator. The altitude scale is around the outer dial ring; it can measure altitude up to 15,000 feet or 4,500 meters (Oris is producing two different models with two different scales, one in feet, one in meters). The air-pressure scale is recessed between the altimeter scale and the central dial. Once the altimeter is no longer needed, the crown can be returned to Position 0 by screwing it down, resealing the watch’s case and ensuring it is once again water-resistant to 100 meters. One of the biggest challenges facing Oris engineers was the design of the altimeter hand itself. Making the altimeter mechanism small enough to fit inside a wristwatch meant the hand had to be extremely lightweight, but stiff enough to avoid tolerances and therefore inaccurate readings. The green area in the illustration below is the Sellita automatic caliber and the blue is the mechanical altimeter. Below the illustration, you can clearly see the clever construction of the altimeter hand, developed with the Swiss specialist Thommen. Oris’s solution was to create the hand from laminated carbon fiber, making it seven times lighter but also 10 times stiffer than the average watch hand.

Yet another challenge was figuring out how to protect the inner workings of the watch from moisture when the altimeter is activated. Oris patented a new altimeter adjustment and venting crown, which prevents moisture from entering the watch using a membrane made of PTFE (a material similar to GoreTex), which creates a vapor barrier. The above-mentioned aspects are all covered by Oris patents, including the multi-function adjustment venting crown, the co-axial layout of the watch and altimeter movements, including a skeletonized movement holder, and the carbon-fiber altimeter hand. Below is a photo of the barometric mechanism as it is integrated into the replica Rolex watches case. Beneath that you’ll find specs and prices for both references of the Oris Big Crown ProPilot Altimeter.

The Oris Big Crown ProPilot Altimeter has a large 47-mm-diameter case and is available with a scale in feet (Ref. 733 7705 4134 TS) or in meters (Ref. 733 7705 4164 TS).

• Oris automatic mechanical movement Cal. 733, based on Sellita SW200, with date indication at 3 o’clock
• Integrated Swiss mechanical barometric altimeter and barometer movement (developed with specialist Thommen)
• Multi-piece stainless steel case, water-resistant to 100 meters
• Sapphire crystal, domed, with nonreflective coating on both sides
• Screwed caseback
• Screw-in stainless steel crowns. Patented altimeter adjustment and venting crown, including PTFE vapor barrier
• Black dial with printed Arabic numerals filled with Super-LumiNova, same as hour and minute hands
• Altimeter handmade from laminated carbon fiber
• Textile strap with stainless steel folding clasp (also available with leather strap or metal bracelet)
• U.S retail price $3,800 with textile strap, $4,100 with metal bracelet