100% cotton flannel. Brushed on both sides for soft velvet feel. Twin/Full fitted sheet fits mattresses up to 12″, Queen/King/Cal King fitted sheet fits mattresses up to 14″ depth. Set includes 1 fitted sheet, 1 flat sheet, and 2 pillowcases (1 for Twin/TXL sizes). Fitted sheet comes fully elasticized for better coverage and fit. Machine washable for easy care. Oeko-Tex Certified, includes no harmful substances or chemicals