I just got this one, it's the second example of this type that I have had. Radiate coins of Constantine are fairly scarce, except for the pretty common half-follis IOVI CONSERVATORI type that were struck by Licinius.
Constantine I
A.D. 320
19x20mm 2.3g
CONSTAN-TINVS AVG, radiate head.
DN CONSTANTINI MAX AVG laurel wreath enclosing VOT XX with * in center.
In ex. PT
RIC VII Ticinum 131
