UNACOO Boys and Girls 3-Pack 100% Cotton Casual Loose Top Crew-Neck Short-Sleeve T-Shirts are quite thick and heavy for a t-shirt. So I would say that they are not for a hot summer day. They don't really look like 100% cotton. They have a lot of stretch. So I sincerely believe it is 100% cotton. In addition, I then washed and they almost did not sit down. So, I think it's actually a cotton-poly blend with some spandex. The size I received was 9-10T. I have no idea what size it is but my 7 year old now wears most of his clothes in a size 8 or medium. They fit him perfectly and have room to grow so I will be wearing these shirts for more than one season. (Unless he gets them too dirty!) So I'd say 9-10 actually equals 8-10 or average. They're a little boxy, but overall a decent t-shirt set. It says 3 packs but you actually get 3 shirts.
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