These are the pillowcases that enable two sleepers with different temperature preferences to remain comfortable throughout the night. Using a fabric developed for NASA to help astronauts adapt to extreme temperature fluctuations, these pillowcases prevent overheating or eliminate chills. Imbedded in the pillowcases are millions of invisible microcapsules that absorb excess heat when you are hot and release the stored heat when you are cold, ensuring a comfortable bed temperature and humidity. Unlike an electric blanket, the microcapsules adjust independently to an individual's climate. The 300-thread count blended cotton fabric is impeccably soft and machine washable. Green, Blue, Sand, White.