Watch List notes:

Constantius I (305-306), Argenteus, Serdica, AD 305-306; AR (g 3,52; mm 20; h 6); CONSTAN - TIVS AVG, laureate head r., Rv. VIRTVS - MILITVM, three-turreted camp gate open; in ex. °SM°SDB°. RIC 11a.
Extremely rare. Lustrous, large flan, about extremely fine.