Prospex Saturation Diver. Designed for those who treat life as the ultimate adventure, the Seiko Prospex line follows every challenge with technological excellence and style. Appropriate for saturation diving under ISO standards, with one-piece case and screwdown crown, this high-intensity watch features a stainless steel case and bracelet with super hard coating and tri-fold clasp with push button release and extender, along with an additional silicone strap. Framed by a ceramic one way rotating elapsed timing bezel, the black dial includes a date calendar and LumiBrite hands and markers, and is topped by a sapphire crystal with anti-reflective coating on the inner surface. The 26-jewel automatic movement beats at a frequency of 28,800 vibrations per hour, with a power reserve of approximately 50 hours, and can be wound manually or automatically. 300m Water Resistant.