A beautiful circular piece.
The coin is definitely rare in this state of preservation.
Obverse: the ruler's head to the left, below it the mint mark F, in the rim the legend:
IOHANN V.G.KOENIG VON SACHSEN;
Reverse: a crowned and order-bound shield of arms, in the rim legend:
XV EIN PFUND FEIN-18-58-ZWEI VEREINSTHALER;