Constantine II as Caesar, AD 316-337. AE Follis 19mm, 2.94 g. Trier. Struck AD 320. 

CONSTANTI-NVS IVN NC, Radiate, draped, and cuirassed bust left
VIRTVS-EXERCIT, Vexillum inscribed VOT XX in two lines; 
bound captive seated to left and right at its base.
Star in left field.
Mintmark STR. 

RIC VII Trier 257 var. (unlisted officina). 

with permission of cngcoins.com, May 2010.