Outerstuff NFL Youth Boys 8-20 Covert Long Sleeve Top Youth Sizing 100% Polyester Performance Tee. Basic Screen Print Graphics Color Please note measurements to find correct size Measurements Youth 8 Small 14 inches Width pit to pit, 21 inches top to bottom 10-12 Medium 16 inches Width pit to pit, 23 inches top to bottom 14-16 Large 18 inches Width pit to pit, 25 inches top to bottom 18 XL 18.5 inches Width pit to pit, 26 inches top to bottom