TS[delta] it is. The TS-for-Thessalonica mintmark wasn't used until after Probus' time. This coin is of Crispus, PRINCIPIA IVVENTVTIS type. I found
this Wildwinds match just by typing into the partial inscription search the only four letters I could read: "PR TS". I had to scroll through quite a lot of coins to find it.

Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis