Maximianus (286-305, 306-308, 310 A.D.) -  Pre-Reform AE Antoninianus of his 1st reign - 21.95x21.15mm, 4.41g
Obverse
IMP C M AVR VAL MAXIMIANVS PF AVG
Maximianus, his radiate and cuirassed bust right
Reverse
IOVI ET HERCV CONSER AVGG
Jupiter and Hercules standing face to face; the former holding globe and
scepter, the latter Victory, club and lion's skin.
Crescent above B in field, XXI in exergue

Minted at the 2nd officina (B) in Antioch (Antakya, Turkey) in 290-294 A.D.

Reference: 
Sutherland, C.H.V., "Roman Imperial Coinage", Volume 5 (RIC), Part II, p294, nr 622.
Sear, D.R., "Roman Coins and their Values" (RCV Millennium Edition), Volume 4, p148, nr. 13134.
Cohen, H, "Descriptions Historique des Monnaies frappees sous l'Empire Romain" (C), Volume 6, p523, nr. 311.
Van Meter, D., "Handbook of Roman Imperial Coins" (VM), p278, nr. 24.
Suarez, R., "Encyclopedia of Roman Imperial Coins" (ERIC II),  p768, nr. 1442 (B69, O33, R104, T81, M02, Exe: crescent over B/XXI)
Suarez, R., (ERIC II-Digital), p639, nr. 1442 (B69, O33, R104, T81, M02, Exe: crescent over B/XXI))
Kampmann, U., "Die Münzen der römischen Kaiserzeit" (K, 2e Auflage), p341, 102.18

Quality: Very Fine+/Extra Fine-
Scarcity: C (Common)