The crown is a mechanism located on the side of the watch case. It serves many purposes in the Rolex catalog, including supplying power to the mainspring and setting the time. Rolex produces a few types of crowns, including the Twinlock and Triplock. When adequately screwed into the case, the Twinlock and Triplock crowns can prevent water, dust, and other microscopic materials from entering the case and damaging the movement. But what, exactly, are the Twinlock and Triplock crowns, and what distinguishes them from each other? Let’s find out.
An older-style Rolex crown vs. the Twinlock crown. Photo Credit: Rolex.
Rolex is credited with inventing the first waterproof wristwatch. The trailblazing invention came in 1926 when the brand officially released the hermetically sealed Oyster case with the patented screw-down crown. Early iterations of the screw-down crown featured a single metal gasket to create the waterproof seal. This design suited Rolex well for many years until it came time to expand its catalog to include a professional series dive watch.
Enter the Twinlock Crown
Instead of a single metal gasket used in previous waterproof Rolex watches, the Twinlock features two synthetic material gaskets and two sealed zones. One gasket is under the crown and helps seal the case, while the second is inside the tube that protects the crown stem. The Twinlock crown made its debut in the 1950s alongside the Submariner but has since been integrated into most models in the Rolex catalog with 100-meter depths ratings.
The Rolex Sky-Dweller 326328 with a Twinlock crown. Photo Credit: Rolex.
What is the Triplock Crown?
The Triplock screw-down crown came to market a few decades later in the 1970s and is larger than the Twinlock crown. To make the case even more water resistant, Rolex equipped the newer crown with two more O-ring gaskets for a total of four gaskets. Despite common misconception, the name “Triplock” is derived from the crown’s three sealed zones and is not associated with the number of gaskets. The innovative design was initially developed for the Sea-Dweller but is now a staple for all Rolex dive watches, including the Submariner, which was upgraded to the Triplock crown sometime in the late 1970s, the Deepsea, and the brand-new Deepsea Challenge.
Rolex Daytona 116500 with a Triplock crown. Photo Credit: Rolex.
The Submariner is waterproof up to 300 meters, the Sea-Dweller up to 1,220 meters, the Deepsea up to 3,900 meters, and the Deepsea Challenge up to 11,000 meters. To resist the immense pressures experienced at such depths, most of the watches in the dive watch category, except for the Submariner, are also outfitted with a Helium Escape Valve. This mechanism allows the gasses that accumulate within the case to escape properly during deep saturation dives, preventing the crystal from popping off and protecting the integrity of the case.
The Helium Escape Valve as seen on the Sea-Dweller 126603. This mechanism is located on the left side of the case. Photo Credit: Rolex.
Dive watches aren’t the only Rolex models to sport the Triplock screw-down crown. In fact, the GMT Master II was recently upgraded from the Twinlock to the Triplock crown alongside the debut of the 6-digit generation in the mid-2000s. The Daytona, Yacht-Master, and Yacht-Master II also use the Triplock crown, while the Air-King, Explorer, Explorer II, and Milgauss sport the Twinlock screw-down crown.
The Rolex Air-King 126900 with a Twinlock crown. Photo Credit: Rolex.
The models housed within the classic Rolex dress watch collection also sport the Twinlock screw-down crown because it is more suited to the proportions of the case than the Triplock crown. Those models include the Day-Date, Day-Date 40, Datejust, Datejust II, Oyster Perpetual, Lady Oyster Perpetual, Lady-Datejust, and Sky-Dweller.
How to Recognize the Twinlock and Triplock Crowns
Aside from the model type, there is another handy way to determine which crown a Rolex watch has. Current-production Rolex watches with the Twinlock crown have very distinctive markings under the Rolex coronet stamped on the crown. Gold watches are distinguished by two dots, platinum watches feature one dot, and stainless steel watches feature a solid line under the coronet. Older-model watches have slightly different markings on the crown; a single bar for yellow gold and stainless steel watches, and two dots for Rolex watches in white gold. The Triplock crown on stainless steel watches is distinguished by three identical dots under the coronet. On gold watches, the center dot is larger and on platinum watches, the center dot is smaller.