Very nice for a nickel sample of the 1949 issue, for which refreshed (cleaned) stamps were used.
The first of the communist period nickel samples offered in this auction - a highly regarded series created on the initiative of Wladyslaw Terlecki and PTAiN, which had a noble idea: to preserve for posterity many trial, circulation or collector issues. They came from the Collection of Miroslaw Zbichorski, who bought them directly from the Mint as the then President of PTN in Bialystok.