Arnold & Son A&S1309

The A&S1309 is a manual-winding movement manufactured by Arnold & Son and introduced in 2009. Still in production, this in-house caliber features a double hemisphere perpetual moon phase complication, simultaneously displaying both northern and southern lunar cycles on the watch dial. The perpetual moon phase mechanism maintains accuracy for 122 years before requiring correction. This movement is used in Arnold & Son's Perpetual Moon collection.