PKO “W” Savings Books
Confusing instrument: it says “Post Office Savings Bank” and “Savings Book” on the front cover but there is a state bond inside:
This bond was issued as compensation for depositors who deposited hard currencies such as dollars or pounds and opened with Post Office Savings Bank deposits denominated in Polish Marks . Due to inflation such deposits became practically worthless as the interest paid did not keep pace with inflation.
For more details please check new entry in my Catalogue of State Bonds of the 2nd Polish Republic: PKO “W” Savings Books.