The Wiardunek was a medieval central European unit of mass most widely used in Poland

Poland

Poland , officially the Republic of Poland , is a country in Central Europe bordered by Germany to the west; the Czech Republic and Slovakia to the south; Ukraine, Belarus and Lithuania to the east; and the Baltic Sea and Kaliningrad Oblast, a Russian exclave, to the north...

 and Germany

Germany

Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

. Wiardunek was also used as a unit of account

Unit of account

A unit of account is a standard monetary unit of measurement of value/cost of goods, services, or assets. It is one of three well-known functions of money. It lends meaning to profits, losses, liability, or assets....

 and as a such as money

Money

Money is any object or record that is generally accepted as payment for goods and services and repayment of debts in a given country or socio-economic context. The main functions of money are distinguished as: a medium of exchange; a unit of account; a store of value; and, occasionally in the past,...

.

As unit of mass:
1 wiardunek (c.49 g) = 1/4 grzywna

Grzywna (unit)

The grzywna was a measure of weight, mainly for gold and silver, commonly used throughout medieval central Europe, in particular Poland, Bohemia and the Rus lands. Grzywna was also a unit of measure of a unit of exchange, and as such used as money. There were several different grzywnas such as the...

1 wiardunek = 4 ounces

In the 14th century, wiardunek took on the role of a unit of account of coin. As such 1 wiardunek was equal to 12 groschen

Groschen

Groschen was the name for a coin used in various German-speaking states as well as some non-German-speaking countries of Central Europe , the Danubian principalities...