This coin has a very large flan-- 25x27mm. Normally they are around 22mm; but despite the large flan, the coin is in the lightweight division...maybe featherweight. It weighs 3.2g and the average for this issue is around 4-5g.
Constantine I
A.D. 310
25x27mm 3.2g
IMP CONSTANTINVS P F AVG; laureate and cuirassed bust right.
SOLI INVI-CTO COMITI; Sol rad., raising r. hand, globe in l.; stg. l., chlamys across l. shoulder, in fields T/F
In ex. PLN
RIC VI London 121a