Picked up another nice Ant of Postumus - I try to pick up any I see for <£10, but I went slightly over budget for this - £10.05. This one is a bit off center on the reverse but the die is crisp. The obverse is well centered and a good strike from a good die, but there is some encrustation.
This is an early issue (COS II), around 260AD (Postumus having captured Gaul in 259AD). The COS I and COS III issues for the same design are very similar.