AR24 - Antoninus Pius L ΔωΔΕΚΑΤΟΥ

Year 12 of Antoninus Pius's reign — the ΔωΔΕΚΑΤΟΥ in the legend confirming the regnal date — places this issue within Alexandria's highly systematized coinage, where Egyptian reckoning ran from the emperor's accession rather than the Roman calendar year. The Alexandrian mint operated under the prefect of Egypt, entirely outside the Roman senatorial monetary system, producing billon tetradrachms for local circulation that rarely left the province.

Milne 1836 is a relatively well-documented die pairing for this year.