This is a First Day Cover that has been hand signed by the great, Don Larsen & Duke Snider. The cachet has been authenticated and slabbed by PSA/DNA. The serial number is verifiable online using PSA/DNA #84092582. The cover comes encapsulated in a tamper-proof cover. 100% authentic signature from Brooklyn Dodgers legend, Don Larsen & Duke Snider. A great gift idea for a Brooklyn Dodgers or MLB collector.