Tudor and its big partner Rolex have been indefinitely postponing the launch of new products in the face of a pandemic challenge in 2021. But this week Tudor finally took the plunge, unveiling a new vintage diving watch in deep blue, the Black Bay 58. Here's what you need to know. The Black Bay Fifty-Eight Navy Blue derives its name from the special blue coloring on its dial and bezel insert — matching the one used on Tudor's dive watches for the French navy in the 1970s — as well as the year 1958, which saw the release of the Ref. 7924 "Big Crown," the first Tudor divers' watch that achieved 200-meter water resistance. The steel case measures 39 mm in diameter — more modest than the 41-mm size of the mainline Black Bay models and more in tune with the proportions of the 1950s dive watches that encouraged it. The blue dial has a grained finish and the hallmark "Snowflake" hands and so many shaped hour markers, all elements derived from vintage Tudor replica watches for divers. The dial, like the sapphire crystal over it, is domed. The ratcheting, steel unidirectional rotating bezel is equipped with a dive-scale insert, made of anodized aluminum in the same matte blue as the dial and featuring silver-gilded numerals and indices. The screw-down crown, with Tudor's historical rose emblem in relief, helps ensure the timepiece's 200-meter water resistance. Ticking behind a solid steel caseback is the self-winding Caliber MT5402, which was developed particularly by Tudor for the Fifty-Eight series' smaller case dimensions. Despite being hidden, the mechanism boasts a high level of Haute Horlogerie flourishes. Its monobloc tungsten rotor is open-worked and features sand-blasted and satin-brushed details, while its bridges and mainplate have a variety of polished and sand-blasted surface treatments. The Tudor Black Bay Fifty-Eight Navy Blue is given on three best replica watches options: a riveted steel bracelet with polished and satin-brushed finishes; a blue "soft touch" strap made of a material resembling flannel. Built with robustness and stability in mind, its variable inertia balance is held sturdily at two points by a traversing bridge, and its silicon hairspring resists the detrimental effects of magnetic fields. The device, certified by COSC, a Swiss testing organization, has what Tudor calls a 70-hour reserve of 'weekend electricity protection.'