Watch List notes:

Constantine I the Great AD 307-337, Siscia Mint, ca. AD 320-321.
Laureate head of Constantinus I right, CONSTANTINVS AVG;
VOT_XX within wreath, DN CONSTANTINI MAX AVG around, in exergue _SIS*
RIC VII 159. Magnificient portrait, sharp reverse, some weakness in lettering. Extremely fine. Size: D: 19.4mm; 2.90g