Complex sentence: In 2006, Mantle was featured on a United States postage stamp, one of a series of four honoring fellow baseball legends Mel Ott, Roy Campanella, and Hank Greenberg.
Split into simpler sentences: In 2006, Mantle was featured on a United States postage stamp. The stamp is one of a series of four honoring baseball sluggers, the others being Mel Ott, Roy Campanella, and Hank Greenberg.