This research highlights a recent discovery, at Poetovio, among a huge number of standard imported Roman oil lamps, of an open-shape copper-alloy lamp to be used with tallow (type Loeschcke XXV). This form, together with its clay counterpart (type Loeschcke XI), is typical of the northern Roman limes provinces where its production and usage was almost exclusive. To understand the uniqueness of this find so far south, the authors have mapped all the known parallels made of different metals. They also present a short introduction to the very eclectic clay variant, which is marginal almost everywhere except for Trier, where it constitutes by far the most common type, quantitatively speaking, of Roman lamps found in situ.