In the short period between 1957 and the mid 1970s Electric Watches reigned. Seiko had five series of these movement calibres, with the Elnix marked as the last Emperor; the most advanced and last transistorized electric watch. The SG, this one, should be considered the pinnacle of the Elnix movement. A Superior Grade NOS edition should live up to expectations and this one does. Indeed, the stickers are still on it!
The electric movement has a battery, also either a balance wheel or a tuning fork and either electrical contacts or a transistor. This however was a very short-lived transitional phase: transistors were just becoming available and mass-produced quartz watches had not yet appeared.
Electric Watches really have died out, the last one was probably made in the mid 1970s. In strict terms, Electric Watches are those without any electronic components i.e. no resistors, diodes or transistors; just a coil, contact and battery.
The watch on sale here is equipped with day-date functions, it also has a smooth sweeping second hand (!) which is a dead give away that it is not a quartz, but to confuse matters, it is also not an automatic...
The fact is, this watch is powered by the 16 Jewels 0703A movement, and a 1.55 volt Silver Oxide Battery breaths life into the movement, not a rotor or a hairspring. It has a frequency of 4 Hz and an amplitude of 8 beats per second or 28,800 bph. That puts it in the same league as a chronometer..
As these watches still use a balance-wheel they should not be confused with quartz-controlled movements or Bulova's Accutron "tuning fork" technology. They are an important milestone; and most of them still run problem free.