These are 100% cotton, but are a thin soft cotton. They are true to size for a boys fit. I compared them to another brand. Just for a reference, I tried it on at 5'1 and wear an XS-Small and the size 9-10 fit me, except the length was too short. The white shirt is see-through, which is normal for a thin white shirt. This would not bother a boy, but may bother a girl. These are a great shirts for the price!
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