here are two Constantine II campgates from Rome that are a bit rarer.
Constantine II
A.D. 318- 319
18x19mm 3.2gm
CONSTANTINVS IVN NOB C; Laureate, draped and cuirassed bust right.
VIRTV-S AVGG; camp gate with three turrets and no doors; P-R across fields.
in ex. RS
RIC VII Rome 173
Constantine II
A.D. 318- 319
19x20mm 3.2gm
CONSTANTINVS IVN NOB C; Laureate, draped and cuirassed bust right.
VIRTV-S AVGG; camp gate with four turrets and no doors; P-R across fields.
in ex. RP
RIC VII Rome --
unlisted, should come after 189