Attraction to the XO Submarine begins with its shape, which significantly impacts the personality of the watch. The large 49 mm case looks square but is actually octagonal if you consider the four chamfered corners. If two lines were drawn through the center of the case diagonally from corner to corner they would form an “X.” The round dial and bezel within represent the “O.” Every XO Submarine has a solid case back affixed by four screws and features a porthole ring design with an image of a submarine (in relief) in the center. The XO Submarine by GV2 offers a lot of value in terms of both style and complexity. The case is tool-inspired and masculine without being bulky, while the series of complications on display has the look of sophistication.