https://www.tonumi.com/catalog/98
Check Period, Lettering, Indentification, Minting, Denomination, Year, Material, Reverse, Obverse. Information about Half-groat, 1495 - 1506 (Undated), Vilnius...
vilnius minthalfgroatcom
https://www.yourdictionary.com/groat
Groat definition: An English silver coin worth four pence, used from the 14th to the 17th century.
groatdefinitionmeaning