Prospex Solar Diver's Watch Powered by light energy - no battery change required 10-month power reserve once fully charged Black uni-directional rotating elapsed timing bezel Black dial Date calendar LumiBrite hands and markers Sapphire crystal Screwdown crown and caseback Case diameter: 42.8mm Stainless steel case and bracelet Tri-fold push button release clasp with secure lock and extender Water-resistant to 200 meters (660 feet), Diver's Watch. Follows ISO standards and is suitable for scuba diving Caliber V157