It's the Slugger logo! .

Printed on:

• Mens/Unisex Shirts: American Apparel Fine Jersey Mens/Unisex (or Royal Apparel 5051). 3XL and 4XL may be substituted with Gildan Ultra Cotton or Hanes Beefy-T in closest color match.
• Ladies Shirts: Bella Fine Jersey Womens Tees (6004). Be sure to check the size charts!