Countermark

https://rpc.ashmus.ox.ac.uk/countermark/1241 
GIC
ΘΕ and unidentified letters or objects
rectangular with curved ends 
12 x 3.5 mm 
compare GIC 707 

Coins with this countermark

Number Image TypeNumber CoinNumber VolumeNumber
RPC I, 1428 Show 1428 18 1