A rare legend variant of the Olkusz trojak, unlisted in Tadeusz Iger's catalog.
Troyak 1593 with titulature started SIG.III, without mint mark (grating), but with REX POLON in obverse legend (which is known for variety with mint mark grating, as in O.93.7.c R3).
Nice condition. Local deficiencies, but good legibility, light patina.