13 oz. flannel lays the perfect foundation for your organic bed. Thick, absorbent flannel, protects the mattress without a lot of extra layers and batting. Designed to be the most natural cover with minimal processing and treatment, our protector is natural in color because it is un-dyed, perfect for even our most sensitive customers. A unique construction of flannel on top and sides with elastic on all sides for a secure fit on the mattress.