A nice piece with well preserved details.
Obverse: head of Augustus in a rosette diadem, to the right, in the rim legend:
CONSTAN-TINVS AVG;
Reverse: camp gate of 7 rows of bricks, with open gate, in the rim legend:
PROVIDEN-TIAE AVGG; in section SMKA-;
Bronze, diameter 18 x 19 mm, weight 2.47 g, axis 12 h.