Initially introduced in 1963, the Seiko 5 wristwatch was conceived to be a basic and affordable timepiece that would appeal to the youth of the 1960's. The idea was to create a mass-produced standardized sub-brand of watches that could be customized in various different ways, while keeping 5 key features that would define it.
Whether you are buying an SKX007, SKX009, or the smaller dial SKX013, one thing you will probably notice is that all three of these watches will have model numbers ending in either a J (J1/J2) or a K (K1/K2). If you were to compare, for example, an SKX007K1 and a SKX007J1, both watches appear to be nearly identical. And both watches have the exact same technical specifications. So what's the big difference between the two?