Countermark

https://rpc.ashmus.ox.ac.uk/countermark/706 
GIC 580
CA
rectangular 
6 x 5 mm 
CAesar? or Caesar Augustus? Probably different cmk from Pangerl 84 

Coins with this countermark

Number Image TypeNumber CoinNumber VolumeNumber
RPC I, 4318 Show 4318 21 1