Mark Teixeira the switch-hitting first baseman signed as a free agent with the Yankees prior to the 2009 season. In his first campaign with the Yankees Teixeira lead the league in both HR and RBI and came in 2nd in the AL MVP voting. He was also awarded a Silver Slugger Award and a Gold Glove. Mark also helped the Yankees win a World Series championship. This Mark Teixeira autograph is guaranteed authentic and includes a Steiner Sports Certificate of Authenticity and an accompanying tamper-evident Steiner Hologram. The Steiner Seal Means Its Real. Steiner Sports is the Official Memorabilia Partner of Mark Teixeira and the New York Yankees. It also includes a Hologram from MLB Authentication.