Undies Organic Kids Etsy Summer children's sleeveless cotton vest undershirt boys base I shaped 3 Pack breathable Cherry Print Baby Undershirts Ely's & Co. Kids Organic Undies Woollykins. Our children's underdress Ylvi is the little sister of our Under Dress Freya and together with our Children's Over Dress Ylva completes the outfit for inquisitive little adventurers. The untreated fabric made of pure cotton is not only comfortable to wear, but also robust enough to meet the special requirements of childlike adventurousness.