Harmon Killebrew Minnesota Twins Autographed Baseball Mini-Helmet MLB HOFHarmon Killebrew autographed Mini Helmet, authenticated by JSA Harmon Clayton Killebrew Jr., nicknamed "The Killer" and "Hammerin' Harmon", was an American professional baseball first baseman, third baseman, and left fielder. He spent most of his 22 year career in Major League Baseball with the Minnesota Twins Very good condition; visible scratching in some spots on the helmet. Autograph presents well with little to no notable smudging, bleeding or