New Era 59FIFTY Boston Red Sox MLB Authentic Collection On-Field Fitted Cap, Navy, Size 7, Model # 70331911. Wear what the players wear! The Boston Red Sox Authentic Collection 59FIFTY Fitted cap features a team color fabrication with an embroidered Red Sox logo on the front and an embroidered MLB Batterman on the back. The New Era flag is embroidered on the wearers left side, and the interior features a moisture absorbing sweatband. Size 7.