Sleep at just the right temperature with 37.5® Technology. Active particles move heat and humidity away, continuously adapting to help keep you comfortable throughout the night. Silky-soft knit fabric is cool-to-the touch. Hypoallergenic for sensitive sleepers. A pillow protector adds an extra layer of protection for your pillow, keeping out dust mites and allergens. We recommend using a pillowcase as well to enclose zippers and tags. Includes:One pillow protector OptionsClassic: Recommended for classic shape pillows.Gusset: Recommended for pillows with gussets to allow for a higher loft.