Countermark

https://rpc.ashmus.ox.ac.uk/countermark/679 
GIC 550
ΛΑΠ
rectangular 
7 x 3 mm 
on coin of Cos, not necessarily applied there. ?=ΛΑΠ or {MA}M  

Coins with this countermark

Number Image TypeNumber CoinNumber VolumeNumber
Show 17