Countermark

https://rpc.ashmus.ox.ac.uk/countermark/265 
GIC 138
male head r.
square or slightly rectangular (one possibly circular) 
c. 5 mm 
on coins of Claudius 

Coins with this countermark

Number Image TypeNumber CoinNumber VolumeNumber
RPC I, 4746 Show 4746 15 1
RPC I, 4746 Show 4746 13 1
RPC I, 4746 Show 4746 12 1
RPC I, 4746 Show 4746 1 1
RPC I, 4746 Show 4746 17 1
RPC I, 4746 Show 4746 16 1
RPC I, 4746 Show 4746 18 1
RPC I, 4746 Show 4746 19 1
RPC I, 4746 Show 4746 20 1
RPC I, 4746 Show 4746 21 1