The 6159-7000 Professional 300m Diver was Seiko's second Hi-beat divers watch. The 6159-7001 is considered to be the grandfather of the SBDX-001. The first only ran for about a year, and they are perhaps the rarest of all Seiko divers. The 6159-7000/7001 was an improvement on the design, and lasted for several years. The movement in it is the same movement that was offered in the 61 series Grand Seiko, except it did not have the 5 adjustments found in the 61 series. First available in 1968 the professional diver's watch 300m used the first high beat highly efficient movement in Japan. The highest-class mechanical caliber was the highest oscillation mechanical movement in the world. There were 3 new casing technologies incorporated into this model: one-piece case structure, rotating-rocking structure of glass fixing structure, and W-type screw down crown.