T-Shirt Universe Little Girls' This Girl is Getting Promoted to Big Sister T-Shirt What kid doesn't love cool t-shirts? Surprise the big sister to be with this fun tee guaranteed to bring smiles to everyone who sees him! This an original design by T-Shirt Universe. Read all the bullets below for specific sizing information. These are 100% heavyweight cotton shirts (Sport Grey is 90/10 Cotton/Polyester.) They are professionally screenprinted with environmentally-friendly waterbased ink. They do run a little small. Please consider ordering a size up. Youth sizing is as follows: Youth X-Small (2-4); Youth Small (6-8); Youth Medium (10-12); Youth Large (14-16); Youth XL (18-20). Youth dimensions are as follows (in inches): Youth X-Small (16" wide and 20.5" long); Youth Small (17" wide and 22" long); Youth Medium (18" wide and 23.5" long); Youth Large (19" wide and 25" long); Youth X-Large (20" wide and 26.5" long.)