Koloa Surf Co. Wave Logo Youth and Adult Heavyweight 6.1-ounce, 100% cotton T-Shirts in Regular, Big and Tall Sizes. A reliable choice for comfort, softness and durability. Heavyweight 6.1-ounce, 100% soft spun cotton. A year-round essential, our best-selling t-shirt has been voted "most popular" by groups, teams, clubs and schools across America.