The 8L55 movement is specially optimized and adapted for use in a diver’s watch with this structure. This caliber beats at 36,000 vibrations per hour and has a power reserve of 55 hours, and it is also assembled by Seiko’s leading craftsmen at the Shizuku-ishi Watch studio.
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 hands, too, are wide and easy to read, and the crystal is made from sapphire, with an anti-fogging coating, for maximum strength and minimum glare.