Here is a coin I just got with the dealer's description.
306-337
Follis
4,83 g, 21-23 mm
Munzstatte: Trier, 310-313
Vs: IMP CONSTANTINVS AVG
Kurassierte Buste mit Lorbeerkranz nach rechts.
Rs: MARTI CONSERVATORI
Kurassierte Marsbute mit Helm nach rechts.
RIC VI 881
RIC only lists Trier as the city that produced these coins, but based on style and obverse die matches with other coin types, London, Ticinum and Aquileia also minted this type.
image from Numismatik Lanz
