Threadrock Big Boys' I'm Going to Be a Big Brother Youth Long Sleeve T-Shirt Threadrock exclusive 100% preshrunk cotton; seamless rib knit collar; reinforced neck and shoulder seams; rib knit sleeve cuffs *Sizing Note* Our youth long sleeve tees run slightly small. For a roomier fit, consider ordering a size up. Sizing: XS (2/4), S (6/8), M (10/12), L (14/16), XL (18/20)