Countermark

https://rpc.ashmus.ox.ac.uk/countermark/675 
GIC 546
ΚΛ | ΙΑ
circular 
5 mm 
Claudius, year 11. Applied at Antioch is likely, but not certain 

Coins with this countermark

Number Image TypeNumber CoinNumber VolumeNumber
RPC I, 4273 Show 4273 9 1
Show 64
RPC I, 4264 Show 4264 17 1