A futon is a flat mattress with a fabric exterior stuffed with cotton, wool, or synthetic batting that makes up a Japanese bed. Futons are sold in Japan at speciality stores called futon'ya as well as at department stores. They are often sold in sets that include the futon mattress (shikibuton), a comforter (kakebuton) or blanket (毛布 mōfu), a summer blanket resembling a large towel (タオルケット taoruketto), and a pillow (枕 makura) generally filled with beans, buckwheat chaff, or plastic beads.[citation needed] Futons are designed to be placed on tatami flooring, and are traditionally folded away and stored in a closet during the day to allow the tatami to breathe and to allow for flexibility in the use of the room. Futons must be aired in sunlight regularly, especially if not put away during the day. In addition, many Japanese beat their futons regularly to prevent the padding from matting. They use a futon tataki (布団叩き), a special instrument, traditionally made from bamboo, resembling a Western carpet beater.