- Under Armour Girls' Size Chart - All Under Armour® Apparel features a tagless design or tear-away tag with no left-over pieces. - Push your limits wearing Under Armour® Kids Rival Ribbed Shirt Sleeve T-Shirt-designed to fuel performance and keep up with every adventure! Featuring a comfortable regular fit, crew neck, and short sleeves, this pull-on tee provides the perfect blend of style and freedom. Whether at play or during training, the ribbed design ensures breathability and durability. Under Armour's mission is simple: to make you better. Set your goals and crush them with game-changing gear built for the bold. - 100% polyester. - Machine washable. - Imported. Measurements: - Length: 18 1⁄2 in - Product measurements were taken using size XL (18-20 Big Kid). Please note that measurements may vary by size.