This Autographed Auto Graded Gem Mint 10 4x5.5 Cut Signature has been Personally Signed by Thurman Munson of the New York Yankees. This item is 100% Authentic, it comes slabbed and authenticated by Beckett Authentication Services.The authenticity can be verified on Beckett Authentication Services website. Press Pass Collectibles only offers Authentic Autographs by Thurman Munson through Signings, In-Person Signings or Private Collections to include a 100% money back Lifetime Authenticity Guarantee.