The Seiko 2E20-5390 watch movement features automatic winding, a frequency of 28,800 beats per hour, a power reserve of approximately 40 hours, and a date function. It has a diameter of 25.6 mm and a height of 5.05 mm, making it a compact movement. The movement contains 21 jewels and has a hacking feature. The Seiko 2E20-5390 uses a Swiss lever escapement and has a balance wheel with four screws for precision regulation. It is equipped with a Etachron fine adjustment system for accurate timekeeping.