20 Nummi - Anastasius I Dicorus Nicomedia, Type ⁑, Large Module

Anastasius I's sweeping currency reform of 512 AD reintroduced large-denomination bronze coins after a century and a half during which the Byzantine monetary system had effectively abandoned fiduciary copper. The new follis and its fractions — including this 20-nummi piece — were a direct fiscal response to the strain of maintaining the eastern frontier and funding repeated campaigns against the Isaurians and later the Persian border wars. Nicomedia, designated with the mint mark NIK, was one of the original mints activated for the reform.

The "large module" designation reflects the brief initial striking standard before the weight was progressively reduced under Justin I.