Unopened 1963 U.S. Proof Set housed in its original Philadelphia Mint envelope. This yellow Treasury envelope is still sealed, with the flap firmly closed and no indication that it’s ever been opened. The envelope shows normal storage wear, light creasing, and handwritten markings from past handling, but remains intact overall. With the contents never exposed, sets like this are valued for their originality and untouched proofs. Please see photos to review the envelope’s condition.