ETA SA SS1K

The Shanghai SS1K is a manual-winding mechanical movement manufactured by Shanghai Watch Factory, introduced in 1972 and produced until approximately 1975. It operates at a frequency of 21,600 vibrations per hour and contains 17 jewels. The caliber is based on the earlier A581 movement, which later evolved into the A611. The SS1K differs from the standard SS1 variant in that it beats at a higher frequency and features a larger balance wheel. Production was discontinued around 1975.