Countermark

https://rpc.ashmus.ox.ac.uk/countermark/676 
GIC 547
ΚΛ | ΙΒ
circular 
5 mm 
Claudius, year 12. Applied at Antioch is likely, but not certain 

Coins with this countermark

Number Image TypeNumber CoinNumber VolumeNumber
RPC I, 4271 Show 4271 17 1