Made of 100% GOTS-Certified organic cotton, the 13 ounce flannel provides a cozy foundation for your infant's bed. This protector is very thick, soft and absorbent, providing superior protection for your crib mattress without extra layers or batting. It is un-dyed and natural in color, perfect for even the most sensitive. Top and sides are flannel with elastic on all sides for a snug fit on your crib mattress.