Vintage Block of 2 Poster Stamps "300" (1958) ?? Lot W-251

Description

This item consists of
Vintage Block of 2 Poster Stamps "300" (1958) ??
Lot # W-251
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I do not know the origin or purpose of these stamps.  If you know, I would appreciate if you let me know. Thank you.  The item in the photos is the item you will receive, please check photos.     These will be shipped in a 1st Class envelope.
I will combine shipping charges if the items are compatible.
I will only ship to addresses in the United States.
E-mail me with any questions, concerns, or clarifications prior to end of sale.   I will be happy to answer any questions.  Thanks for your interest and for bidding.  Please try to pay within 4 days of the auction close.
I will make every effort to ship the item quickly & securely.   I would appreciate feedback upon satisfactory delivery and I will leave positive feedback for you as well.
If there is any problem with the item, please contact me so we can work it out.