This Autographed Lee MacPhail Oal Baseball with the inscription of "Good Luck" has been Personally Signed by Thurman Munson of the New York Yankees. This item is 100% Authentic to include a Certificate of Authenticity (COA) / hologram by JSA. The authenticity can be verified on JSA 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.