Countermark

https://rpc.ashmus.ox.ac.uk/countermark/645 
GIC 518
rectangular 
4 x 3 mm 
Later cmk's grouped with those of Hadrian. Some doubt if one or two groups? 

Coins with this countermark

Number Image TypeNumber CoinNumber VolumeNumber
RPC III, 2719 Show 2719 3 3
RPC III, 2719 Show 2719 4 3
RPC III, 2719 Show 2719 2 3
RPC III, 2719 Show 2719 6 3
RPC III, 2719 Show 2719 5 3
RPC III, 2719 Show 2719 7 3
RPC III, 2719 Show 2719 8 3
RPC III, 2719 Show 2719 9 3