"Cool" is the new standard. This classic cotton cover has been infused with technology developed for NASA so there's no more flipping to the "cool side". It's love at first squeeze.Rest your head on the pillow designed for the best support and perfect sleeping temperature. The cover is infused with a heavy coating of space aged Outlast technology. The 300 thread count, 100% cotton outer shell keeps absorbs, stores, and releases heat as your temperature changes throughout the night.Features:300 thread count, 100% cotton outer cover for soft, breathable comfortNASA-approved Outlast lining fabric on both sides fights off heatLuxury 100% down alternative fiber-fillOeko-Tex Standard 100 Certified TechnologyFilled in the USATwo firmness levels allow for perfect neck supportDesigned to manage heat through your pillowcaseEasy to Care For: Just throw it in your home washing machineTechnology: Traditional bedding and moisture wicking technologies react to changes in your body temperature while you sleep. Slumber Cloud® is doing something different.Slumber Cloud® Bedding utilizes Outlast technology for a unmatched approach to temperature regulation. Outlast technology is proactive, not reactive. As your body temperature increases during sleep, Outlast technology stores that heat to keep you cool, and then releases it as you cool down...keeping you feeling just right.Materials: Our premium lining fabric takes a proactive approach by employing active temperature control properties, versus other "cooling" bedding that is moisture-wicking and simply reactive.Benefits: Outlast materials improve comfort for: Anyone looking for a more comfortable night's sleep - they'll sleep cooler! Women experiencing menopause - hot flashes and resulting night sweats are reduced so they sleep cooler and drier. Thermally incompatible couples - individuals sleep at their own ideal temperature.Research: We pass on everything we learn to our customers. From sleep studies to new technologies, we want to help you make informed decisions about your sleep.Size Guide:Pillows : King : 20" x 36"Pillow Covers : King : 21" x 37"Firmness Guide:We recommend to pick your firmness based on your typical sleeping position.Soft/Medium:The soft-medium pillow offers the perfect support for those that prefer to sleep on their stomach and back or want a softer pillow.Medium/Firm:The medium-firm pillow is recommended for those who regularly sleep on their side and back or want a bit firmer pillow.® Registered Trademark of Global Web Horizons LLC dba Slumber Cloud Slumber Cloud Outlast Core Down Alternative Pillow - King