The Shanghai caliber A581 is a 17 jewels (17 zuan) manual wind mechanical movement. It is based off the A. Schild caliber AS 1194. This caliber was produced from circa March 1958 – 1967. This caliber does not have the following: no anti-shock protection system; no adjustment screws on the balance wheel; no fixing screw on the main bridge.
Similar movements in this family include the Shanghai caliber A611 with an anti-shock system, as well as the caliber A623 with a date complication.