We Match! Keep Calm We're On A Family Vacation T-Shirt Matching Family Flip Flop Shirts (Kids - Adult) We Match! uses only high-quality fabrics for the best feel and durability. Premium heavyweight 6.1 ounce 100% cotton. Short sleeves. 6.1 oz., pre-shrunk 100% cotton. Please see the images for the official We Match! size charts. The ones provided by Amazon are not accurate. Youth XS (2-4); Youth Small (6-8); Youth Medium (10-12); Youth Large (14-16). Adult sizes run true to size.