With no dye or bleach our Long Sleeved Crew in 100% silk is the most natural layer available for your sensitive baby or child. Silk is as warm as wool of the same weight, so this soft, 100% silk underwear will keep your precious little one as warm as if it were wearing merino wool, but with no danger of itching. Silk is naturally temperature regulating, so your child won't be too warm or too cold, it'll keep them just right!