Following the "Specialized catalog of Polish coins of the 20th and 21st centuries". by Mr. Jerzy Chalupski, we come across the following: "August 26, 1939. The President of the Republic of Poland signed a decree published on the same day introducing steel coins with denominations of 20 and 50 groszy into circulation. Steel fifty-groszy coins were to be introduced into circulation and function in parallel with nickel coins."
A coin so far erroneously attributed to the General Government, but actually minted already during the Second Republic.
Piece without numerical grade due to cleaning marks. Detail without traces of circulation, graded UNC.