A nice piece with good details.
Obverse: head of Augustus in laurel wreath, to the right, in the rim legend:
CONSTAN-TINVS AVG;
Reverse: camp gate of 10 rows of bricks, with open gate, in the rim legend:
PROVIDEN-TIAE AVGG; in fields Delta-E, in section SMANT;
Bronze, diameter 20 mm, weight 2.92 g, axis 5 h.