Boston Red Sox 2018 Official Batting Practice Onfield Cap - Red/Navy. Material: 100% Polyester, High Crown, Structured fit, Flat bill with ability to curve, Fitted, COOLERA ® technology wicks away sweat, DRYERA ® technology repels weather-related water, ProLight hats feature a featherweight polyester fabric that is 25% lighter than previous fabrics for maximum comfort and versatility, Wipe clean with a damp cloth, Six panel construction with embroidered graphics, Silicone New Era flag, Beveled rubber badge logos.