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. Based on Seiko’s Speedtimer precision chronographs of the early 1970’s, which added style and function to appeal to young motorsports enthusiasts, this superbly tailored timepiece features a specially designed thin case, curved to seamlessly connect to the bracelet for enhanced sport elegance and wearing comfort. Providing chronograph measurement of up to 12 hours of elapsed time in 1/8-second increments, the proprietary caliber 8R48 34-jewel automatic movement beats at a frequency of 28,800 vibrations per hour, with a power reserve of approximately 45 hours and manual winding capability. The movement includes a column wheel and vertical clutch mechanism allowing for smooth, stutter-free movement of the chronograph hand while providing long-term efficiency, reducing wear and tear and maintaining the power reserve better during chronograph operation. For reliable timing, the three-pointed hammer system ensures that all hands return to zero instantly and in perfect synchronization when the re-set pusher is pressed. The classic black dial, framed by a contrasting white dial ring, features white subdials and a red chronograph hand echoing the colors of the original models, as well as a date calendar and LumiBrite hands and markers. Adding a note of tailored luxury, the multi-row bracelet provides a sleek, comfortable fit. Crafted of stainless steel with a super-hard coating, this extraordinary timepiece also features a dual-curved anti-reflective sapphire crystal, screwdown caseback, and tri-fold push button release clasp. 10 bar, 100M Water Resistant