The reverse is totally blank, one can only read on the obverse the countermark TONZOY, which is over an oval countermark that is illegible. Just for the sake of it, can anyone guess who the emperor on the coin is? It came with the description "Claudius, AE25, TONZON countermark over oval countermark of head right, Howgego 568" but I don't think it is Claudius. Maybe Domitian or Trajan? 25 mm, 10.995 g Countermarked in Thrace, Tonzos
Doesn't look like Augustus. Then maybe Trajan. I don't have Howgego and it seems that Howgego, Greek imperial countermarks. Studies in the provincial coinage of the Roman Empire, London 1985 (= Royal Numismatic Society. Special Publication No. 17), is not available on line. Internet Archive says: "This book is not available at this time"...
Howgego doesn't state that Augustus and Trajan are the only options; but they are merely the only ones noted by the author. Theoretically, any emperor from Augustus to Trajan could be included.
Have read that the city of Tonzos located at the river Tonzos would later become Hadrianopolis. What I can't find is the oval countermark which seems to be struck after the TONZOY countermark