Could be a barbarous imitation of the 4th century .The size of the imitations followed the size of the official coins, wich were smaller and smaller .As we see in the 3th century the Gallic imitation (Tetricus I ,II , ..) have a diameter of 15-18 mm , these of the 4th cent. are approximately 8 mm ( minimi ) or app. 4 mm (minisimi ),these last one often of bad quality . Most of these coins were inspired on the mint of Lugdunum (Lyons) , with on the obverse an imperial bust or a personification (Roma or Constantinopolis) . The inscription has most of time no sence .The reverse is often worse than the obv . albert