This campgate has a "seen from the back" bust, versus the normal draped and cuirassed. It's not that rare, merely rated scarce in RIC for this workshop, but it is a nice portrait of Crispus with an uncommon bust type.
Crispus
A.D. 324- 325
19mm 3.1gm
FL IVL CRISPVS NOB CAES; Laureate, draped and cuirassed bust seen from behind.
PROVIDEN-TIAE CAESS; camp gate with two turrets and star between them.
in ex. PTR
RIC VII Trier 450