REEF 39.5mm Automatic Chronometer 300M - Preorder

Contact us at sales@windupwatchshop.com if you are interested in purchasing an additional bezel.

The Formex REEF 39.5mm brings professional dive watch specs to a refined, compact platform. Sized down from its 42mm sibling, this version delivers 300 meters of water resistance, a screw-down crown, ceramic bezel, and box-shaped sapphire crystal — all in an 11mm-thick case that wears comfortably at 45.5mm lug-to-lug.

The dial is clean and highly legible, with applied indices, a 6 o’clock date window, and generous Super-LumiNova for low-light readability. Offered in bahama blue, blue, white, or silver, with a 120-click ceramic bezel that rotates with smooth, precise feedback. Every model comes fitted on Formex’s stainless steel bracelet, which includes their patented on-the-fly micro-adjust clasp for quick, tool-free sizing. That quick change feature also extends to the bezel, which can be swapped in seconds — allowing for easy customization without compromise.

Powering the REEF 39.5 is the COSC-certified Sellita SW300-1 automatic movement. It features a 56-hour power reserve, hacking, hand-winding, and beats at a smooth 28,800 bph. Visible through a sapphire caseback, it’s a reliable, Swiss-made engine that elevates this diver beyond expectations.