Although this tuning fork movement was designated by Omega as a caliber 1260, the base movement is an ESA (Ebauches S.A) 9164. The ESA 9164 features a day and date. Caliber ESA 9162 (Omega caliber 1250) has a date only.
The large Omega caliber 2211 is found in the XXL Seamaster Aqua Terra Railmaster. This pocket watch movement is a manual wind with 17 jewels and a 53 hour power reserve. It is a certified chronometer (COSC).