Probus (276-282 A.D.) -  AE Antoninianus - 22.18mm, 3.15gr
Obverse - IMP C M AVR PROBVS P AVG
Probus, his radiate, helmeted and cuirassed bust left,
holding spear over shoulder and shield.
Reverse - PROVIDENT AVG
XXI in Exergue. T in right field.
Providentia standing left, holding globe and transverse scepter.

Minted in Siscia (Sisak, Croatia) in 277 A.D.

Reference:  
Webb, P.H., "Roman Imperial Coinage", Volume 5, Part 2 (RIC), p94, nr. 723, obverse bust G, var. with T in reverse left field.
Suarez, R., "Encyclopedia of Roman Imperial Coins II" (ERIC II),  p662, nr.220 var (B15, O34, R113, T107, M6, exe: T/XXI)
Van Meter, D., "Handbook of Roman Imperial Coins", p261, nr 37, var. with Ol/5.
Alföldi, A. "Probus Sisciai antoninianusai", Type 53/47

Quality: Fine-
Rarity: Unknown