Seiko SUS Military Style Automatic - 4S15
This is the Seiko SUS military-style automatic watch. I refer you to an excellent discussion of this watch at this link by Ryan. The pictures are gone, but there is an excellent explanation of the SUS (a watch line by Seiko.) I learned a lot from his excellent post. In summary, the line was conceived to introduce to a new generation of Japanese youth, what was for them a novel concept: the analog watch. Two Seiko engineers were put in charge of the project. Teenagers were polled. The resulting line includes some fine watches. Probably the most famous and sought out is the Military SUS, which seems to have gone into production beginning in 1995 or 1996, lasting a couple of years. Click here to see another unique view of this watch.

With design quotes, and functional adaptations from military, aviation and railroad timekeeping devices, the military SUS is replete. There are exquisite details: the date is there if you need it, but it's so subtle as to be almost hidden. The hour hand is not only substantially shorter than the minute hand, it is also slightly wider, decreasing ambiguity, and furthering the ease of time reading.  Dial is high contrast and easily readable. Hacking seconds hand.
The case is very interesting. It's a robust piece of steel, having a heavy bezel. The bezel reminds me of a Cyma British military watch. The case is also "distressed" or blasted in some way, to give the appearance of wear. It's really a beautiful case (more.)
There are some features which would not normally (or ever) be found in a real military-issued watch. The crystal is highly reflective flat synthetic, which could be disadvantageous in the military environment. While the hands are luminous, the dial lacks any luminous material. Also, most military watches do not have the date. Finally, there is a display back! A "crystal" covers the back so the movement is visible, which is never a feature of a military watch.
This seemed to be the feature which "stuck out" the most on this watch. Seiko has other military style watches, and none of them have display backs. I never understood why this watch should have it, but thanks to the article by Ryan, now I think I do. Seiko, in introducing this line, purposefully installed their high-grade movements. This watch has the 4S15 caliber. It is a 25 jewel movement with a shockprotected high-frequency escapement (Hi Beat.)  It seems that the Seiko engineers were proud enough of the movement, that they wanted it to be seen and appreciated, when they kicked off the SUS line. But I think there's more: if these watches were being designed for Japanese youth, who had only known of digital watches, what better way to acquaint them with analog timekeeping and mechanical movements than to show them the very act in progress, to show them the movement? I really wonder if this may have played some role in adding a display back.
The longer I keep the SUS, and the more I learn about it, the more I like it. I owe this watch to a friend, from Japan. He knows who he is, and he knows what he did for me to help me get this watch! This watch will never be for sale. A few more pictures below, thanks for reading.

Chitoshi Funamoto and Atsushiko Matsuno, Seiko watch engineers.
Detail of case distressing treatment.
The Seiko SUS, being reflected back in the mirror-like crystal of another Seiko watch. The double image (see especially the zero of the "10") is cause by parallax, from double reflections; one from the inner surface of the second Seiko's crystal, and one from its outer surface.
Another military style Seiko, with lovely luminous.
Click below picture to see the original SUS catalog.
(Watch is not for sale)