Rare type of portrait, R3 in the Roman Imperial Coinage catalogue.
Roman Imperial
Constantine I the Great (308-324), Follis 325-326, Heraclea mint
Obverse: diademed head of Constantine I to right
CONSTANTINVS AVG
Reverse: around wreath containing VOT XXX in two lines, SMHΔ in exergue
D N CONSTANTINI MAX AVG
Diameter 20 mm, weight 2.87 g