Polyester. Referee Shirt Set: You will get black and white striped referee shirt, penalty flag and stainless steel whistleproviding a complete set for sports referees. Comfortable Referee Costume: 100% non-shrink polyester men's ref shirt is quick drying and lightweight; stainless steel whistle and flexible penalty for a better experience. V-Neck Referee Shirt: The referee shirts are designed with a V-neck for easy on/off and elasticated cuffs for a comfortable fit. Professional Ref Shirt for Men: The referee costume with vertical black and white stripes for a professional look. Suitable for all kinds of sports events. Umpire Shirt for Multiple Occasions: Suitable for football, soccerbasketball and other sports, as well as events, restaurants, bars and Halloween costumes.