XSB (3-4 Years) MB (7-8 Years) LB (9-11 Years) XLB (12-13 Years) Small (34-36") Medium (38-40") Large (42-44") XL (45-48") XXL (50-52") SB (5-6 Years) Womens XS (Size 8 - 30"Chest) Womens S (Size 10 - 32"Chest) Womens M (Size 12 - 34"Chest) Womens L (Size 14 - 36"Chest) Womens XL (Size 16 - 40"Chest) Womens XXL (Size 18 - 40"Chest)