It was minted in Arles. Here is the description I got from wildwinds.
Decentius, AE3 of Arles. DN DECENTIVS CAESAR, bare-headed, cuirassed bust right, A behind head / VICTORIAE DD NN AVG ET CAE two Victories standing facing each other, holding between them a wreath inscribed VOT V MVL X. C over IS in lower centre. Mintmark SAR. RIC VIII Arles 182; Sear 18884.