Image rights: wildwinds.com

Constantine II AE follis of Cyzicus. AD 337-348. 
CONSTANTINVS IVN NOB C, laureate, draped, cuirassed bust right.
GLOR-IA EXERC-ITVS, Two soldiers standing facing each other; 
each holding a spear and resting hand on shield, one 
standard between them. 

Mintmark SMKS. 

RIC VII Cyzicus 123; Sear 17361.