Apparently only the second known specimen in the world with an inverse Z mintmark in exergue!
Obverse: radiate, cuirassed bust right, legend:
IMP PROBVS AVG;
Reverse: Emperor riding left, right hand raised, left hand holding sceptre; captive at foot, legend:
ADVENTVS AVG; In exergue Rᴗ•INVERSE Z;
Silver, diameter 22 mm, weight 3,04 g, axis 6 h.
From the collection of a true connoisseur of Probus’ coinage