Another coin that came in the group lot of "plated" coins that just arrived.. Maybe thrown into the group lot since it was assumed to be too light to be a genuine Justinian Solidus at just 3.7 grams without evidence of clipping, but.. The reverse legend is OBXX instead of CONOB Which is on regular solidii "obryzum viginti siliquae (gold of 20 siliquae)." which was added to lightweight solidii valued at 20 Siliqua - and were possibly minted for for trade with foreigners or as tribute payments..
Nice! Here is a better picture of the exergue on a lightweight solidus so people can see the difference easier.