The Cool Sleep pillow features ventilated Gel Memory foam, which is a unique material that infuses gel particles into viscose-elastic memory foam, creating a plusher and cooler sleeping material. In addition the Cool Sleep Gel Foam Pillow responds to temperature and pressure to mold to your shape by creating the perfect support for your head, neck and shoulders. The Performance knit pillow cover is made from Cool Pass fabric, which is designed to keep the surface of the pillow cooler. The fibers in the Cool Pass fabric are shaped and formed by the specific ' X ' shaped cross section that speeds up the moisture absorption and diffusion.