A very nice, slightly deficient piece.
Variety with the date at the bottom of the reverse legend.
Obverse: royal bust in crown, armor and cloak, with tubular orifice seen from the side, to the right, in the rim legend:
SIGI-3-D-G-REX-PO-M-D-L-;
Reverse: denomination mark III, below it the coats of arms of the Crown Eagle, the Sheaf of the Vasa dynasty and the Pose of the Grand Duchy of Lithuania, below it the legend in three lines GROS-ARG/TRIP-REG/POLONI, below it the coat of arms of the Levart in a shield divides the date 15-98, on the sides initials I-F;