A nice piece.
More interesting, not described in Kopicki and in CNG, a variant with the abbreviation CIVITA
Obverse: in the pearl rim the coat of arms of Gdansk, in the outer rim the legend:
IIOIIET○CIVITA○DA;
Reverse: in the pearl rim a shield with a crowned eagle, in the outer rim legend:
KASIMIRVS○REX○:;
Silver, diameter 20 mm, weight 1.06 g.