This 1976 First Day Issue Envelope celebrates the INTERPHIL philatelic event held in Philadelphia. It features four 13 cent stamps that showcase the beauty and history of the United States. The envelope has been previously owned, but is in good condition for its age. It would make a great addition to any stamp collection and is perfect for both novice and experienced collectors. The authenticity of the stamps is not certified, but they are ungraded and have been well-preserved.