Countermark

https://rpc.ashmus.ox.ac.uk/countermark/515 
GIC 395
caps of the Dioscuri
square 
4 x 4 mm 
a later cmk than GIC 394. Perhaps the two caps, rather an one, were depicted to distinguish the two groups of countermarks 

Coins with this countermark

Number Image TypeNumber CoinNumber VolumeNumber
RPC VI, 8291 (temporary) Show 8009 4 6
RPC VI, 8273 (temporary) Show 7991 3 6