In addition to being smooth and silky to lay your head on, silk pillowcases are beneficial for both your hair and skin. 100% 19 momme mulberry silk, a sensuously smooth, strong, hypoallergenic and breathable natural, organic fiber helps prevent wrinkles, dry skin, and morning bed head. Envelope closure is designed to prevent any occasional scratching of metal/plastic zippers so the silk lasts longer. 20 x 30 inches (51 cm x 76 cm) fits most queen-sized pillows. 20 x 36 inches (51 cm x 92 cm) fits most king-sized pillows.