Countermark

https://rpc.ashmus.ox.ac.uk/countermark/670 
GIC 541
ΚΑΙ
rectangular 
8 x 4 mm 
Caesar. Applied to Hellenistic coins, probably in early imperial period 

Coins with this countermark

Number Image TypeNumber CoinNumber VolumeNumber
Show 8
RPC I, 1733B Show 1733 3 1