Prospex Speedtimer Mechanical Chronograph. Designed for those who treat life as the ultimate adventure, the Seiko Prospex line meets every challenge with technological excellence and style. Celebrating Seiko's first precision chronographs, developed for international sporting competitions in 1964, as well as its 1969 introduction of the world's first automatic chronograph, this exceptional watch provides chronograph measurement of up to 30 minutes of elapsed time in 1/8-second increments. The 34-jewel automatic movement, visible through the screwdown see-through caseback, beats at a frequency of 28,800 vibrations per hour, with a power reserve of approximately 45 hours and manual winding capability. The proprietary 8R46 movement includes a column wheel and vertical clutch mechanism allowing for smooth, stutter-free movement of the chronograph hand while providing longer wear and efficiency, and maintaining the power reserve better during chronograph operation. Crafted of stainless steel with super-hard coating and tri-fold push button release clasp, this extraordinary timepiece also features a charcoal gray dial with beige LumiBrite hands and markers topped by a dual curved anti-reflective sapphire crystal. 10 bar, 100M Water Resistant