Shanghai Watch Factory Caliber SS1

Manufacturer	Shanghai Watch Factory (上海)
Caliber Number	SS1, SS1A, SS-1, SS-1A
Based On	Shanghai A581
Jewels	17
Beats per hour	18,000 vph
Power Reserve	40 hours
Anti-Shock System	None
Hand-Windable?	Yes
Hacking Seconds?	Yes
Functions	Hours, minutes, central seconds
Country of Manufacture	China
Known Models	(Add yours to the comments below)

The Shanghai caliber SS1 (also written as SS-1) is a 17 jewels (17 zuan) manual wind mechanical movement. It is based off of the original Shanghai caliber A581 (which evolved into the A611). This caliber was produced from circa 1966 – 1972.

There will be two letters above the caliber number. This is the date code for when the movement was manufactured.

There is a similar movement in this family known as the SS1K which beats at a higher 21,600 bph.