Trust Me I'm Gonna be a Big Sister on Infant & Toddler Cotton T-Shirt (in 21 colors) This shirt runs small. Please order next size up. See sizing under Product Description below. Genuine South Horizon product. Sold exclusively by South Horizon 100% cotton jersey. Heather is 90% cotton, 10% polyester. Available in Infant and Toddler sizes. See sizes under PRODUCT DESCRIPTION below.