With many different calibers, the Silverwave Quartz was definitely present in the seventies. Hot on the heels even it was of the 94 Superior (9481/83), but also the Grand, King and Quartz series, respectively 9461, 9443 and 9441 or even the maverick Lassale 9442. This twin quartz then is something special indeed, produced at the end of the twin quartzes in the early eighties.
Still, at about half the price of a King Seiko, but above the Type II, a caliber like the 9441 inside a Silverwave case is very robust packaged, more so than inside the King Quartz case. As such it was an experiment by Seiko to make a water resistant watch that can take a punch. The tsunami caseback logo is used to denote specific attributes. It is used to signify a watch that is intended to get wet and it has shown up on various waterproof/diver watches from the old Silverwave through the pro and other divers of today.
For the discerning collector, the tsunami logo comes in several different forms, with small, one or two waves, up to the realistically rendered full wave. A good rule of thumb is that the bigger the wave rendered the greater the watches water resistance and performance attributes (Diver’s watches all come with the full tsunami caseback logo).
Silverwaves then are all about the casing, one can expect a screw down crown at 3 or 4 o'clock with crown guard and a screw in case back – even a unidirectional bezel. Most other Quartzes were not so equipped, sporting a battery hatch for example and a push crown. Looking at the dial legibility is key, especially at night. The markers of a Silverwave certainly can be all lume, the hands then of course as well, and the seconds hand even has that lume tip usually found in divers.
So a very sporty watch, tough, manly angular and well prepared for the active lifestyle of the get up and go businessman or maybe even a blue collar worker?