Sized to accommodate chest protector (order one size smaller if wearing on bases) Made of unique Birdseye Fabric Moisture Management Technology Soft, Breathable, and Wrinkle-Free Added Stretch for On-The-Go Comfort United Attire Baseball Umpire Shirts are designed to provide ultimate comfort while retaining a professional look, inning after inning. Made of special Birdseye Fabric reserved for the most premium apparel in the sporting industry, these jerseys combine the absolute best in both function and comfort.