Watch List notes:

City Commemorative. A.D. 330-354. AE reduced follis (15.5 mm, 1.61 g, 7 h). Uncertain mint, struck ca. A.D. 330-333. VRBS ROMA, crested and helmeted bust of Roma left wearing imperial mantle / Victory standing facing, head left, in prow of galley, holding inverted spear and resting hand on shield; illegible mint mark in exergue. RIC -; LRBC -. aVF, granular surfaces.

This is either a mule of the URBS ROMA / CONSTANTINOPOLI type or a barbarous imitation. It is slightly smaller and of a slightly cruder style than official mint coins leading me to believe it is probably a barbarous imitation in relatively high style.