Seiko SSA391

The Seiko reference SSA391 has a steel case measuring 42.4 mm across. The case has a thickness of 14.5 mm, with a water-resistance rating of 100 metres. The movement is self-winding calibre 4R37, which contains 24 jewels and has a power reserve of approximately 41 hours. The watch has a curved Hardlex crystal. The band is a leather strap; the seconds hand can be stopped. The see-through case back has a screw construction. The distance between the lugs measures 21 mm. The dial has LumiBrite on the hands and indices.