Countermark

https://rpc.ashmus.ox.ac.uk/countermark/892 
GIC 758
denominational mark Β
oval 
6 x 5 mm 
Uncertain (Uncertain)
At the time of writing GIC no other Bithynian coins with a B countermark were known 
List of countermarks View on a map

Coins with this countermark

Number Image TypeNumber CoinNumber VolumeNumber
RPC VII.2, 1967 Show 1967 21 7.2