Designed with a stainless steel case and bracelet, this 41.0mm Grand Seiko Caliber 9R66, features the signature Grand Seiko clear ridges on the facets of the case and the diamond-cut hands and markers with red 24-hour hand on a black dial. Spring Drive, a unique Seiko movement that requires neither a battery nor an electric motor, makes it a completely self-contained system. Its power is derived from a mainspring, just like a mechanical watch, and its accuracy is controlled by the precise signal of a quartz oscillator. These watches are all accurate to ±10 seconds per month, a level that is higher than any other existing spring-wound watch in the world. Spring Drive movement allows for self and automatic winding capabilities and features 30 jewels, with accuracy /- 1 second per day with over 72 hours power reserve. 100M Water Resistant