Copper Roman coin

I am working on my Ancient knowledge. Hints on the best way to search this one? Been searching on 'O KΛΑ'. I know it is Roman and one of the Constantines.

1.6 grams, 17mm

You mean what original coin is it a replica of, as to me it does not look ancient.
This says it is Greek
https://en.numista.com/catalogue/exonumia31488.html

Obverse: Profile of Constantine
Lettering: Constanti

Reverse: Crossed shields and crossed spears
Lettering: Ο ΚΑΑ ΥΙςω