100% pure habotai silk.  Seamless sheets. 15 momme The sheets are sold in sets. Each set includes a bottom fitted sheet, a top flat sheet, and one standard pillow case. The fitted sheet is encased in elastic with a 15" pocket for a range of mattress depths. Care: Hand or machine wash gently in cool water with mild soap. Air or machine dry - cool setting for about ten minutes. Remove from dryer immediately. 15 momme. Silk is so much finer than cotton it is measured by momme, or weight. Total Twin Sheet Set weight: 1 pound, 4 ounces. Provide relief for bed-ridden patients. Twin set fits most hospital beds. "Thanks for the silk sheets. I have been in a hospital bed for one month and this is the first thing that feels soothing against my skin."