A nice piece.
Undescribed in Kopicki's variant with POLO legend.
Obverse: in the pearl rim the coat of arms of Elblag, in the outer rim the legend:
+MONETA:CIVIT:ELVI;
Reverse: in the pearl rim a shield with a crowned eagle, in the outer rim legend:
*KASIMIRVS:R:POLO;
Silver, diameter 19 mm, weight 1.13 g.