Fortis B-42 Marinemaster Chronograph 638.10.41 M. Fortis B-42 Marinemaster Chronograph watches are the ultimate instrument for professional divers. Each timepiece is equipped with Swiss-made Valjoux 7750 automatic calibre that performs 28 800 vibrations per hour and has 25 bearing jewels. Other movement characteristics include Incabloc shock absorber and fine timing device. Hands, numerals and indices are covered with luminous paint to enhance night time readability. A day and date display is positioned at the 3 o'clock mark. The watch's chronograph comes with a 60-second, a 30-minute and a 12-hour counter. Additional useful features include a rotating bezel that measures elapsed time, screw-down case back, individual numbering and scratch-resistant sapphire crystal glass with anti-reflective coating.