Constantine  I Magnus (307-337 A.D.) -  Silvered AE3 - 19.36mm, 3.22gr
Obverse - CONSTANTINVS AVG
Constantine, his laureate head right.
Reverse - PROVIDENTIAE AVGG,
Campgate with six rows, two turrets,  no doors,
star above, top and bottom row blocks.
SMKB dot in Exergue
Minted at the 2nd officina in Cyzicus (Balkiz, Turkey) between 324 and 325 A.D.

Reference:
Bruun, P.M., "Roman Imperial Coinage", Volume 7 (RIC), Cyzicus, p647, nr 24, obverse 1-B1
Failmezger, V., "Roman Bronze Coins From Paganism To Christianity 294-364 A.D.", nr 352jCI
Carson, R.A.G., Hill, P.V., & Kent, J.P.C., "Late Roman Bronze Coinage",  Part I, p28, nr 1187
Sear, D.R., "Roman Coins and their Values" (RCV 4th Revised Edition), p326, nr. 3878, variety with SMKB dot mint mark.
Van Meter, D., "Handbook of Roman Imperial Coins", p292, nr 85

Quality: Very Fine+ with crack at 180 degrees