This Autographed Pinstripe Cooperstown Collection Authentic Mitchell & Ness Jersey with the inscription of "573 HR's" has been Personally Signed by Harmon Killebrew of the Minnesota Twins. This item is 100% Authentic to include a Certificate of Authenticity (COA) / hologram by Beckett Authentication Services. The authenticity can be verified on Beckett Authentication Services website. This is a Medium sized Jersey.