Constantine II, AE follis of Rome.

CONSTANTINVS IVN NOB C, laureate, draped, cuirassed bust right.
VOT X-ET XV F-R squiggle CT in three lines within wreath.
(Mintmark is the 3rd line)

RIC VII Rome 206.
Extremely rare. Rated R5.

With permission of Roma Numismatics, Aug. 2014.