The large Omega caliber 2211 is found in the XXL Seamaster Aqua Terra Small Seconds (reference: 188.8.131.52.06.001). This pocket watch movement is a manual wind with 17 jewels and a 53 hour power reserve. It is a certified chronometer (COSC). Based on a ETA Unitas 6498-2. The older and discontinued Railmaster XXL was equipped with essentially the same movement known as caliber 2201. The differences are cosmetic.