Hocosa of Switzerland Organic Wool-Silk Snap-Bottom Shirt with Short Sleeves, for Baby & Toddler Made of 70/30% blend of soothingly soft Euopean KbT- certified organic merino wool & silk. Wool for warmth. Silk for strength and softness. Natural fibers breathe, maintaining a comfortable temperature in warmth or cold. Even when damp, wool feels warm, unlike cotton & synthetics. Naturally flame-retardant, without chemicals, making it perfect as infant sleepwear or under-layer. Natural wool with lanolin gives self-cleansing properties, minimizing need for washing. For best results, wash occasionally by hand with lanolin-replenishing woolwash to maintain hygienic effects. For best fit - European size correlates to full length in centimeters. (Baby's length in inches x 2.5). For For chunkier babies, choose next size up.