Countermark

https://rpc.ashmus.ox.ac.uk/countermark/1429 
Martini, Pangerl 105
CEK (Latin) or ϹΕΚ (Greek)
circular 
9 mm 
applied in Syria to Tiberian dupondii 

Coins with this countermark

Number Image TypeNumber CoinNumber VolumeNumber
RPC I, 3868 Show 3868 17 1