The dial design has just one objective; maximum legibility, even deep in the ocean where sunlight does not penetrate. The hour markers are large, so as to allow the maximum surface area and depth for Seiko’s Lumibrite coating.
The crown has screw-down protection to prevent it from being pulled out by any accidental operation.
The precise and secure operation of the uni-directional bezel prevent accidental rotation, so that the time measured is never shorter than the actual elapsed time.
200 m (20 ATM)