On May 16th at Safeco Field, the Red Sox and Mariners will don throwback Negro League jerseys to honor the players who were barred from playing in the major leagues. The game will be part of a four-game set between the two teams. The Mariners will wear the jersey of the Seattle Steelheads—a Negro League franchise of the mid-1940s. The Red Sox will wear the jersey of the Boston Royal Giants. Over the years, the Royal Giants played games at Medford's Playstead Park, Boston's Lincoln Park, Braves Field and Fenway Park.