Seiko Prospex Watch Diver SPB051J1. These new timepieces also echo the design of the 1965 original, but are thoroughly up to date in their functions and meet Seikos stringent standards for divers watches. The hands are wider and carry long lasting Lumibrite so as to be highly legible even in dark water. The water resistance has been increased to 200 meters and the crystal is sapphire for greater strength and durability and has an anti reflection coating. The watch sits perfectly on the wrist and the Zaratsu polished line on the case side adds a touch of contemporary refinement. One is an all steel version, while the other features an accordion style silicone strap which combines high durability and comfort. The accordion style strap was invented by Seiko in 1975 as a solution to the problem of the expansion and contraction of a divers wrist at different depths.